# Thread: Sine/ Cosine. solve for x

1. ## Sine/ Cosine. solve for x

Solve for x
A. sin30°=x/12
b. cos136
°=5/x
c. sin5
°=26/x
d sin x=5/12
e. cos x=2/15

i need help.

2. You're going to need a calculator for four of these. The first is elementary:

$\sin 30 = \frac{x}{12}$

$x = 12 \sin 30 = 12(0.5) = 6$

For b and c: rearrange the equation.

For example,
$x = \frac{5}{\cos 136}$

Then it's plug and chug.

d and e are similar.

For d:
$x = \sin^{-1}(5/12)$

You have no choice but to use the calculator on both of these. Note that $\sin^{-1}$ is the inverse sine function.

3. thank you