Question

Help me with 3 problems !

Answer 1

can you work out angle B ?

Answer 2

im so lost with this

Answer 3

you should know that the sum of the angles in a triangle equals 180°,

Answer 4

so

A+B+C=180°


A is given as 20°
and C is a right angle ie 90°

Answer 5

ok

Answer 6

arent i supposed to solve this using a trigonometric function?

Answer 7

b=70...?

Answer 8

we will use trig functions for the sides,

but we should find the missing able first,

yes B=70°

Answer 9

now lets find the sides,

what does sine 20° = ?

Answer 10

sin 20* = 12/x

Answer 11

yes , but the hypotenuse (x) is equal to c

Answer 12

oh yeah

Answer 13

12/c

Answer 14

good, so you have sin 20° = 12/c

solve this equation for c

Answer 15

wait why would it be sin?

Answer 16

sine will help us find c

Answer 17

why? sorry for asking

Answer 18

because we are solving for \(\triangle ABC\), we need all the angles and sides,
we now have all the angles, we can work out the missing sides with trig

Answer 19

yeah but how do you know which one to choose?

Answer 20

sine theta is opp/hypo, we have theta and we already have the opp side,

Answer 21

cosine wont work yet, because cosine of theta is adj/hypo, we have theta, but we dont have adj, or hypo

Answer 22

we can use tangent theta = opp / adj to find the adjacent side

Answer 23

so it can either be cosine or tangent?

Answer 24

so find all the side we will use both

Answer 25

ok so for sin 20* = 12/c , what equation do i do?

Answer 26

you need to isolate c,

multiply both sides by c and divide both sides by sin(20°)

Answer 27

which ones cancel out?

Answer 28

there is no cancelling this time, you'll probably want to express these sides as decimals