Question

Evaluate each of the following cos 60° cos 45° − sin 60° sin 45°

Answer 1

SOLUTION :

Given :  

cos 60° cos 45° – sin 60° sin 45°                                                                                          

= ½ × 1/√2 − √3/2 × 1/√2

= 1/2√2 − √3/2√2 = (1 - √3) / 2√2

cos 60° cos 45° – sin 60° sin 45° = (1 - √3)/ 2√2

[cos 60° = 1/2 ,  cos 45° = 1√2 , sin 60° = √3/2,   sin 45° = 1/√2]

Hence, cos 60° cos 45° – sin 60° sin 45° = (1 - √3) / 2√2

HOPE THIS ANSWER WILL HELP YOU…

Answer 2

Detailed and rationalised answer