Question

高中数序三角函数是怎么化简成的,

Answer 1

( π / 4 + x ) + ( π / 4 - x ) = π / 2

两角互余,

y = 2 sin ( π / 4 + x ) cos ( π / 4 - x ) = 2 sin ( π / 4 + x ) sin ( π / 4 + x ) = 2 sin^2 ( π / 4 + x )