Question

Answer 1

a: sin 2*a=sin90=1

2*sina*cosa=2*sin45*cos45=1

=>sin2a=2*sina*cosa

b: \(1+cos2a=1+cos90=1\)

\(2cos^2a=2\cdot\left(cos45\right)^2=2\cdot\dfrac{1}{2}=1\)

=>2cos^2a=1+cos2a

c: \(1-cos2a=1-cos\left(2\cdot45\right)^2=1\)

\(2\cdot sin^2a=2\cdot\left(sin45\right)^2=1\)

=>2sin^2a=1-cos2a