Hello from MrBillDoesMath!
Answer:
sqrt(15)/4
Discussion:
The attachment shows a right triangle where arcsin(@) = 1/4. (The arcsin means find the angle whose sine is 1/4 as is done in the triangle.) The missing side, sqrt(15), shown in red, was determined by the Pythagorean theorem.
Then cos(@) = cos(arcsin(1/4)) = sqrt(15)/4
Thank you,
MrB
D. g(x) = (x - 3)²
Hope this helps bih :)