(cos(80°)-cos(40°))/sin(40°) = ?

1 Answer
Oct 8, 2017

sqrt 33

Explanation:

We know, cos C - cos D = - 2 sin(C + D)/2. sin (C - D)/2

Hence,[ cos 80 - cos 40]/sin 40cos80cos40sin40

rArr [ - 2 sin (80+40)/2. sin (80-40)/2]/sin 402sin(80+40)2.sin(8040)2sin40

rArr [ - 2 sin 60. sin 40]/sin 402sin60.sin40sin40

rArr - 2 sin 602sin60

rArr - 2. sqrt 3 /2 = - sqrt 32.32=3