Question

Помогите с В7, пожалуйста:* Алгебра

Answer 1

                              Решение:

 

tg66=tg(90-24)=ctg(24)
cos^2(114)=cos^2(90+24)=sin^2(24)
10cos^2114tg66=10sin^224*ctg24=5sin48
1-2cos^2111=-cos222=-cos(270-48)=+sin48
(1-2cos^2(111))/(10cos^2114*tg66)=sin48/5*sin48=1/5 или =0,2.

Answer 2

(1 - 2cos²111°)/(10cos²114°*tg66°) =  (sin²111° + cos²111° - 2cos²111°)/(10cos²114°*tg(180° - 114°)) =  (sin²111° - cos²111°)/(10cos²114°*tg114°) = (sin²111° - cos²111°)/(10cos²114°*sin114°/cos114°) = -(cos²111° - sin²111° )/10cos114°*sin114° = -cos222°/5sin228° = -cos(360° - 138°)/5sin(360° - 132°) = -cos138°/5sin132° = -cos(180° - 132°)/5sin132° = sin132°/5sin132° = 1/5 = 0,2.