If A+B+C=180∘. Find sin2A+sin2B+sin2C =
We know conditional identities but all of them are in the form of degree one.Here, power of sine is 2.
First we should reduce this power to 1 and then simplify it
We know cos2A=1−2sin2A
= 32−12 cos2A+cos2B+cos2C....(1)
∴ given expression becomes 2+2cosAcosBcosC