Question

Найдите значение выражения:-7sin76градусов/сos38град*cos52град

Answer 1

$-frac{7sin(76^circ)}{cos(38^circ)cos(52^circ)} =\\= -frac{7sin(2*38^circ)}{cos(38^circ)cos(90^circ - 38^circ)} =\\= -frac{7(2sin(38^circ)cos(38^circ))}{cos(38^circ)sin(38^{circ})} = boxed{-14}\\ left[ sin(2a) = 2sin(a)cos(a); cos(90^circ - a) = sin(a) right]$

Answer 2

СПАСИБО!!!