Всё на фото............. Created by Данякеп. geometriya-ru

Всё на фото...

Данякеп @Данякеп

August 2022 1 38 Report

Всё на фото............

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oganesbagoyan

Verified answer

Task/26548526
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17.
12 / (sin²37°+sin²127°) =12 / (sin²37°+sin²(90° +37°) =12 / (sin²37°+cos²37°) =
12 /1 =12.
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18.
6 /(cos²23° +cos²113°)=6 /( cos²23°+cos²(90° +23°) ) =6 /(cos²23° +sin²23°) = 6/1 =6.
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19.
12/ (sin²27° + cos²207°) =12/ ( sin²27°+ cos²(180° +27°) ) =
12/(sin²27° +cos²27°) =12/1 =12.
* * * cos(180 ° +27°) = -cos27° ; cos²(180 ° +27°) = (-cos27°)² =cos²27° * * *

Все примеры можно решать по другому
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например 17.
12 / (sin²37°+sin²127°) = 12/( (1-cos2*37°) /2 +(1- cos2*127°)/2 ) =
-6 / ( cos74°+ cos254° -2 )  = -6 / (2cos(254 -74)/2 *cos(254 +74)/2 -2 ) =
-6( cos90°*cos164° -2) = -6 *(0 -2)  = 12.

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