Hi Guys.

am stuck with a few trigo questions here ...

1) Find value of sin10 + sin50 - sin70 without using calculator

2) Prove that sin(A+2B) + sin(A-2B) = 4sinAsinBcosB

3) If A =36 , show that sin3A = Sin 2A and find cos 36

Appreciate your help guys !

Thanks !