Question

Cos²30° + cos²60° + cos²90° + 2 cos 30° cos 60° cos 90°​

Answer 1

1

Explanation:

`cos²30° + cos²60° + cos²90°\\ + 2 cos 30° cos 60° cos 90° \\ \\ = \bigg( ( √(3) )/(2) \bigg) ^(2) + \bigg( ( 1 )/(2) \bigg) ^(2) + \bigg( 0\bigg) ^(2) \\ + 2 * ( √(3) )/(2) * ( 1 )/(2) * 0 \\ \\ = (3)/(4) + (1)/(4) + 0 + 0 \\ \\ = (3 + 1)/(4) \\ \\ = (4)/(4) \\ \\ = 1`