Mathematics
Senior High
Solved

cos170°のところで何を使ってこの式になっているのか教えてください🙇

x 266 (1) cos 80° = cos (90° -10°) = sin 10° sin 100° = sin (90° +10°) = cos 10° よって nja, 80s cos 170°= cos (180° -10°) = -cos 10°

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