Question

Why sin c is written as 2sinc/2cosc/2

Answer 1

From double-angle formula we know that:


`\sin(2\theta)=2\sin\theta\cos\theta`

so (for θ = c/2):


`\sin c=\sin(2\cdot(c)/(2))=2\sin((c)/(2))\cos((c)/(2))`