Evaluate 3cos 55°/7sin35° - 4(cos70°×cosec20°) / 7(tan25°×tan5°×tan45°×tan65°×tan25° )
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Answer:
-1/7
Step-by-step explanation:
cos55°=cos(90°-35°)=sin35°
cos70°=cos(90°-20°)=sin20°
tan5°= tan(90° - 85°) = cot85°
tan25°=tan(90° - 65°) = cot65
tan45° = 1
3cos 55°/7sin35° - 4(cos70°×cosec20°) / 7(tan25°×tan5°×tan45°×tan65°×tan85° )
= 3sin35°/7sin35° - 4 (sin20*cosec20°) / 7 (cot65° × cot85° × tan45° × tan65° × tan85°)
= 3sin35°/7sin35° - 4 (sin20*cosec20°) / 7 (1/tan65° × 1/tan85° × tan45° × tan65° × tan85°)
= [3/7 - 4 /7]
= -1/7
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