Rewrite as product of trig functions Sin PI11 sinPI4 Rewrite

Solution

Solution:

=> Sin(pi/11) + sin(pi/4)

using identity;

Sin A + Sin B = 2sin{(A+B)/2} cos{(A-B)/2}

=> Sin(pi/11) + sin(pi/4)

= 2sin{(pi/11 + pi/4)/2} cos{(pi/11 - pi/4)/2}

= 2 sin (15pi/88) cos (-7pi/88)

Let we know, cos(-x) = cosx

= 2 sin (15pi/88) cos (7pi/88)