Answer: cos(Θ) = (√15) / 4
Explanation:
The question states:
1) sin(Θ) = 1/4
2) 0 < Θ < π / 2
3) find cos(Θ)
This is how you solve it.
1) Use the fundamental identity (in this part I use α instead of Θ, just for facility of wirting the symbols, but they mean the same for the case).

2) From which you can find:

3) Replace sin(α) with 1/4
=>

=>

4) Given that the angle is in the first quadrant, you know that cosine is positive and the final answer is:
cos(Θ) =

.
And that is the answer.
Step-by-step explanation:
I've posted solutions in the picture. Rather the ways to solve them. Check and find answers on your own.
Also, I've not solved the problem by differential calculus. You can, obviously, if you're interested. Use it for ease and for tougher equations.
31 is g = -19
32 is x = -9
34 is w = -11
31:
g-(-7) = -12
g+7 = -12
g = -19
32:
-5x = 45 divide by -5
x = -9
33 looks like it has a print error so I can’t figure that out, I don’t know where the |-2| is supposed to be
34:
(w-1)/4 = -3 multiply by 4
w - 1 = -12
w = -11