Question

if sin a=1/2 a is acute, then find (3cosa - 4 cos^2a)

Answer 1

Hey... I think this can be ur answer!!

Sin a =1/2
Sin a = sin 30
a = 30 degrees

Now,
3 cos a - 4 cos2 a
3cos 30 - 4 cos2 30
3(root3/2) - 4 (root3/2)2
3root3/2 - 3