Question

sin(a) + cos(a) = $\frac{1}{3}$
sin(2a) = ?

Answer 1

(sin a+cos a)² = sin² a+cos² a+ 2sin a×cos a=1+sin(2a),

 (1/3)²=1+ sin (2a)

sin (2a) = (1/3)² -1 = 1/9 -1= -  8/9