Question

If A=sin2π/7 + sin4π/7 + sin8π/7
B=cos2π/7 + cos4π/7 + cos8π/7
Find the value of √(A^2+B^2)

Answer 1

Answer:

√(3+2cos(2π/7)+2cos(4π/7)+2cos(6π/7))

Step-by-step explanation:

The detailed solution is long , this is just a walk through:

Hint 1 :(a+b+c)^ = a^2+b^2+c^2+2ac+2ab+2ac

Hint 2 : cos(a-b)= cos(a)cos(b)+sin(a)sin(b)