Suppose the angle A satisfies 0 Solution0 A

Solution

0< A <2pi

cosA =0.75 ; sinA <0

A is in IVrth quadrant

sinA = - sqrt( 1- cos^2A) = -sqrt(1- 0.75^2) = -0.66

sinA = -0.66

sin(A/2) :

sin(A/2) = sqrt{ [ 1- cosA]/2} =sqrt{ [ 1- 0.75]/2}

= 0.35

cos(A/2) = sqrt{ [1 +cosA]/2 } = sqrt{[1+0.75]/2}

= 0.935

tan(A/2) = sin(A/2)/cos(A/2) = 0.35/0.935 = 0.374