Задача 12503 (cos^2a*cos^2b+2sina*sinb*cosa*cosb+sin^2a*sin^2b)/cos(a-b)...

mari_nuzhnaya

23.12.2016

(cos^2a*cos^2b+2sina*sinb*cosa*cosb+sin^2a*sin^2b)/cos(a-b)
Упростите

SOVA

23.12.2016

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cos^2a·cos^2b+2sina·sinb·cosa·cosb+sin^2a·sin^2b=
=(cosa*cosb+sina*sinb)^2=cos^2(a-b)

(cos^2a·cos^2b+2sina·sinb·cosa·cosb+sin^2a·sin^2b)/cos(a–b)=cos^2(a-b)/cos(a-b)=cos(a-b)