Question

$sin^{2} l*cos^{2} b - cos^{2} l*sin^{2} b$

Answer 1

Ответ:

Объяснение:

sin²l×cos²b-cos²l×sin²b=(sinl×cosb-cosl×sinb)(sinl×cosb+cosl×sinb)=

sin(l-b)×sin(l+b)=[cos(l-b-l-b)-cos(l-b+l+b)]/2=(cos(-2b)-cos2l)/2=(cos2b-cos2l)/2