SOLUTION: If {{{ sin^2(pi/9) + sin^2(2pi/9) + sin^2(3pi/9) + sin^2(4pi/9) = 9/4 }}}, without the use of a calculator, evaluate {{{ cos^2(pi/9) + cos^2(2pi/9) + cos^2(3pi/9) + cos^2(4pi/9)

Algebra ->  Trigonometry-basics -> SOLUTION: If {{{ sin^2(pi/9) + sin^2(2pi/9) + sin^2(3pi/9) + sin^2(4pi/9) = 9/4 }}}, without the use of a calculator, evaluate {{{ cos^2(pi/9) + cos^2(2pi/9) + cos^2(3pi/9) + cos^2(4pi/9)       Log On