Question

Find the exact value of cos(arcsin( one fourth )). For full credit, explain your reasoning. (2 points)

Answer 1

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