Question

Derive a formula for sin(2????) in terms of sin(????) and cos(????) for all real numbers ????.

Answer 1

Answer: sin (2α) = 2 sin (α) cos (α)

Explanation:

We departure from the sin of a sum of angles

sin ( α + β ) = sinα *cosβ + sinβ *cosα

if α = β ⇒ sin (α + α ) = sin(α) *cos(α) + sin(α)*cos(α)

sin (2α) = 2 sin (α) cos (α)