Question

Evaluate each of the following cos² 30° + cos² 45° + cos² 60° + cos² 90°

Answer 1

SOLUTION :

cos² 30° + cos² 45° + cos² 60° + cos² 90°            

= (√3/2)² + (1/√2)² + (½)²  + 0

= ¾ + ½ + ¼ + 0

= ¾ + ¼ + ½ + 0

= (3 + 1) /4 + ½

[ By taking L.C.M]

= 4/4 + ½

= 1 + 1/2

= (2+1)/2 = 3/2

[ By taking L.C.M]

cos² 30° + cos² 45° + cos² 60° + cos² 90° = 3/2

[cos 30° = √3/2   , cos 45° =1/√2 , cos 60° = 1/2 ,  cos 90° = 0]

Hence, cos² 30° + cos² 45° + cos² 60° + cos² 90° = 3/2.

HOPE THIS ANSWER WILL HELP YOU…

Answer 2

cos²30= 3/4 + cos²45=1/2 +cos²60=1/4 +cos²90= 0

hence 3/4+1/2+1/4 = 3+1+2 ➗ 4 = 6/4

ur answer is 3/2


I hope my answer is correct ^ω^