Using Half-Angle Identities to Solve a Trigonometric Equation (7.7.3)

Question 1

• Half-angle identities allow you to write trig functions of an angle x/2 (half of the angle x) in terms of trig functions of the angle x:

• cos x/2 = +/- sqrt(1+cosx)/2.
• sin x/2 = +/- sqrt(1-cosx)/2.
• tan x/2 = +/- (1-cosx)/sinx.

Answer 1

• Half-angle identities allow you to write trig functions of an angle x/2 (half of the angle x) in terms of trig functions of the angle x:

• cos x/2 = +/- sqrt(1+cosx)/2.
• sin x/2 = +/- sqrt(1-cosx)/2.
• tan x/2 = +/- (1-cosx)/sinx.