trigonometric function

Question

Write the following expression in u (assuming u>0):

 

sin arccos (3)/(√4u²+9)

Answer 1

cos^-1 3/(√(4u² + 9)) implies that the adjacent leg is 3 and the hypotenuse is √(4u² + 9).

Using Pythagoras, the opposite side is √4u², or 2u

The sine is 2u/(√(4u² + 9)).