Question

Could I find the two missing angle measures if I know some of the side lengths of a right triangle?

Answer 1

Yes you could.

Answer 2

how?

Answer 3

use trigonometry... to find 1 angle... sin, cos or tan.

you have 2 angles... find the 3rd, since the triangle is right angled you can use angle sum of a triangle..

Answer 4

can you show me an example?

Answer 5

sure





\[\cos(x) = \frac{12}{13}.... then...... x = \cos^{-1}(\frac{12}{13})\]


then you ahve found the 1st angle.

the other angle is found by 180 - 90 - x

hope this helps

Answer 6

im still confused :/

Answer 7

ok... well do you know about trigonometry..?

Answer 8

i understand for the most part sin cos tan but im not the best at applying it. I was thinking for this it would be the sec cosec and cotan but idk.....i h8 geometry :/

Answer 9

ok... so what is cos equal to in terms of the sides of a triangle... opposite, adjacent and hypotenuse..?

Answer 10

soh-cah-toa.....cos is adjacent over hypotenuse

Answer 11

yep

so in the diagram cos(x) = 12/13

how do you find an angle using trig.?

Answer 12

idk :/

Answer 13

ok... heard of arccos..... of cos^-1..?

Answer 14

you have lost me

Answer 15

ok... do you have a calculator handy...?

Answer 16

yeah but i have to type up an example and explain for my project

Answer 17

so here is an online calculator

http://web2.0calc.com/

press the buttons 2nd cos then 12/13) and =

it will tell you the size of angle x in degrees...

Answer 18

well its helping your understanding.

Answer 19

what answer do you have for the size on angle x

Answer 20

.3947

Answer 21

nope... try again, 2nd then cos

the screen says acos(

type in 12/13)

then press equals...

Answer 22

when i do that it is cos-1

Answer 23

pressing 2nd cos will display acos.... which is the same as cos^-1

it stands for arccos

Answer 24

.39479117

Answer 25

does you calculator display radians or degrees...?

Answer 26

idk its the online ti-84+silver edition

Answer 27

ok... well I have one of them when I press 2nd cos ( 12/13) I get 22.62

can you press the mode key... and look at the 3rd item in the menu... radian degree

make sure degree is highlighted

Answer 28

also check the next option is func and not pol

Answer 29

ok now i got the same answer as you :)

Answer 30

it was in radian :/

Answer 31

ok... so with 2 sides you have found an angle.

you know the triangle has a right angle

so you just need to find the 3rd angle

this can be done by angle sum of a triangle...

call the 3rd angle A

then 180 - 90 - 22.62 = A


so A = 67.38 degrees

so really you only need 2 sides in a right triangle to find the 2 angles...

hope this makes sense.

Answer 32

ok THANK YOU SO MUCH :)

Answer 33

glad to help.