Question

Prosze o dokladne rozpisanie jak to obliczyc ;D

Answer 1

2sin²18* + sin²72* + cos²18* =2sin²18* + sin²72* + cos²(90* - 72*) =

2sin²18* + sin²72* + sin²72* =2sin²18* + 2sin²72* =

2 *(sin²18* + sin²72*)  =2 * [ sin²(90* - 72*) + sin²72*) ] =

2 * [ cos² 72* + sin²72* ] =2 * 1 = 2