Sin Cos Tan - Basic Trigonometry - Working unknown angles - Free Educational videos for Students in K-12

Sin Cos Tan - Basic Trigonometry - Working unknown angles - By tecmath

Transcript


00:0-1	Good day and welcome to Tech Mouth Channel . What
00:02	we're gonna be having a look at this video is
00:03	the third video just looking at trigonometry . Okay .
00:07	It's really , really simple sort of stuff , trigonometry
00:10	once you get the hang of it . Um the
00:13	first video , we were just looking about how to
00:14	go through and label sides and things like this and
00:18	all the different economic functions that you might use .
00:21	Only the last video , we looked at how to
00:22	work out an unknown side on a right angle triangle
00:26	. Using trigonometry . This video , we're gonna be
00:28	having a look at the working at unknown angles .
00:30	Okay , that's pretty simple sort of stuff though .
00:33	And you just need to follow a few basic rules
00:35	. So first off , what you have to be
00:36	able to do is realize that with the right angle
00:39	triangle , we have this longest side which is called
00:41	the high pot News . And also we have to
00:44	be able to label these other sides according to this
00:47	angle here , the angle we may be trying to
00:49	work out or the angle which were given which we
00:52	call theater . The one opposite theater is called the
00:55	opposite . The one adjacent is called the adjacent .
00:57	So the first step you wanna be able to do
00:59	it label these . We look at this in the
01:01	first video . We also used in the last video
01:04	. You also want to remember the uh different economic
01:08	functions . These ones here . The sign cause Tan
01:12	. Uh so this is the scientific calculator . In
01:15	the computer calculator . You will then a scientific calculator
01:18	to do this . You'll see that we have sign
01:21	cause Tan will also be using this inverse function in
01:25	this particular part . Okay . Uh , you also
01:29	might see this occasionally records signed by this one and
01:31	that sort of deal . So the functions we have
01:33	to know was sign equals opposite over high point news
01:37	cause equals adjacent over hypotenuse and tan equals opposite over
01:41	adjacent . Remember with that lovely pneumonic , some old
01:46	hags can't always hack their old age . So if
01:48	you can remember this , you're doing pretty well because
01:51	we just follow these particular steps when we solve these
01:53	true economic questions , we first we label the sides
01:56	, we work at the true economic function . That's
01:58	at first two things we did , then then we're
02:00	going to substitute values were to solve it . It's
02:03	fairly simple . So let me give you an example
02:06	here . So you get this sort of question .
02:10	Um , we have this particular question . We have
02:13	this right angle and we have this particular shape here
02:18	. In fact , I might elongate this a little
02:20	bit of , let's make it a little bit a
02:22	little bit longer . Okay , so So we had
02:26	this and what I want to do is I'm going
02:29	to give it some lengths . Okay , I'm gonna
02:31	give it a length here , which will be what
02:34	we call this 17 . And I'm going to give
02:36	this one over here , right ? And what I
02:39	really , really want to know more than anything in
02:40	the world is , I want to know what this
02:43	angle here is , what theater is . We can
02:46	use trigonometry to work this out . Okay . This
02:49	is really basic stuff to you'll get this really ,
02:52	really quickly . So first off , you have to
02:54	label the sides . So it's sides are we dealing
02:57	with ? We're dealing with the opposite and we're dealing
03:00	with the adjacent . Okay . I'm no longer gonna
03:04	put into this hypotheses . We're not using it more
03:06	label it . So we're dealing with the opposite in
03:08	the adjacent . So you might remember that . So
03:10	we've done that . We've labeled the sides . Now
03:13	we can work it out to economic function . Some
03:15	old hags can't always hack their old age . So
03:23	we're dealing with , we were dealing with the O
03:24	. And the A . One which is 10 .
03:27	Okay , let's get rid of these ones were not
03:29	dealing with . So we're dealing with tad . Yeah
03:32	. Okay . So Tan theater , the leaders ,
03:37	what we're trying to work out equals the opposite Over
03:41	the adjacent equals the opposite , which is eight Over
03:46	the adjacent , which is 17 . So if we
03:49	were to work out this in the calculator , we
03:50	go , we put this up here . And what
03:53	I do is I go , I know it's gonna
03:56	be sitting smack Bang in the middle of nowhere .
03:58	Good all the time . But eight divided by 17
04:02	. This equals uh for .0.4705 . I'm just gonna
04:07	write this down . You're gonna get in stage .
04:08	You don't need to Equals 0.4 seven . Okay .
04:15	Tan theater equals is now the way that we work
04:17	out theater is that we go theater equals this about
04:23	but we don't , we hit Tan but we're gonna
04:25	hit this as a negative one town , the inverse
04:28	of Tan . So we got this number here and
04:31	we do this , we go in verse 10 and
04:35	we get 25.2 . That is our answer . It's
04:39	a 25.2 degree angle . Did you get that ?
04:45	So instead of this time just hitting tam , we
04:47	actually have to hit the inverse in here . Okay
04:50	. Or on some scientific calculation level , like a
04:54	second function button and it will go to this thing
04:56	you'll see written above . It will have this minus
04:59	one up here or something like this . That's all
05:01	you have to do for these guys . So let's
05:03	give it another example here . Uh , what about
05:07	we do a different one again ? Like I said
05:10	, the last video , I'm not going to try
05:12	like , so I lied in the last video .
05:14	I did deliberately make it particular functions and I ,
05:18	um , but this one I'm going to see which
05:21	one it never comes out . Okay . I'm not
05:22	gonna , I'm just gonna try and through them relatively
05:26	quickly , but not a silly and we will use
05:30	the hypothesis . So let's , let's call this one
05:32	X . And I'm going to do this one here
05:34	, which is , I'm going to call 15 and
05:38	we're going to do the theater here . We don't
05:41	know that is , okay , So first off ,
05:44	let's label the sides . Okay , We're not using
05:47	the opposite . We're using the adjacent the high part
05:50	news so we've labeled decides work at the true economic
05:53	function . Okay . So is it some old hags
05:57	can't always hack That's actually this one isn't that you
06:01	can see that already . Don't even need to finish
06:03	their old age park . So it's cause co sign
06:06	equals adjacent over hypotenuse . So because feta equals adjacent
06:16	over hypotenuse . Can't always hack equals ah What about
06:23	doing corn that X . By the way , we
06:26	know this side here . Oh man . We're real
06:29	Duffy . Sometimes I'll put this side back in there
06:32	. Really good . I didn't go making the wrong
06:34	color . Good good . Real winner of a video
06:37	this one . But it won't matter , will it
06:41	? Okay . This time we do know what I
06:43	was saying here . We do know this was going
06:44	to give it some random value . Let's call it
06:46	17 . Okay . Can't be a smaller than they
06:52	kind of wouldn't work with it . Um so let's
06:54	call it 17 . So 50 Over 17 . Okay
07:01	. Jason over the high part news . And so
07:05	what do we get ? We're gonna have data here
07:07	equally . 15/17 . This should be equal to the
07:13	coast side , But it's the -11 . Okay .
07:17	So we can hit this all in one fell swoop
07:20	here . Okay , let's do this . We go
07:22	15 divided by 17 equals in verse Co side .
07:31	It's 28°. . All right . Okay . This equals
07:34	28°. . Cool . Yeah . And you won't make
07:39	mistakes . This is telling me who's right . Making
07:41	mistakes running up questions . Oh man . I should
07:44	screw us a bit better . One last long last
07:46	guy . Okay . I'll try to make it assigned
07:49	one . Does that sound a lot of fun ?
07:51	So this is what we have here . Okay .
07:55	We have , We want to know three tower .
08:00	We have the opposite . We have the opposite ,
08:02	which is five . We know the high part news
08:04	which is eight . Let's solve this now . I
08:07	told you it's a sign one . Okay . Let's
08:09	label it . First off we have the opposite .
08:12	We have the high part news . Uh sub old
08:16	eggs . So sign FIFA equals opposite . 5/8 .
08:25	Okay , so feta equals 5/8 , Signed to the
08:30	-1 . Let's work this out . five divided by
08:35	eight equals side . Oh wrong 15 divided by eight
08:41	equals inverse . Sine . It was 38.7°. . It
08:47	was 38.7°. . Pretty easy . Right ? Anyway ,
08:53	hopefully that was some help . I know that last
08:55	one was a bit of a rush . I'll tell
08:56	you a bit of a hint . I can actually
08:58	hear my Children coming in the house right now about
09:01	to ruin my video and make lots and lots of
09:03	noise . So I did rush through that last one
09:05	anyway . Hopefully that wasn't too rushed for , you
09:08	know , that last part . Thanks for watching this
09:10	. Any questions , any difficulties , any mistakes that
09:14	I made her . But you know , that would
09:15	never happen . Let me know anyway . See you
09:17	next time , But .

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