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Sec 70° Sin 20°- cos20 cosec70 = 2 |
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Answer» Answer: Step-by-step explanation: sec 70° sin 20° + COS 20° cosec 70° = sec (90° - 20°) sin 20° + cos 20° cosec (90° - 20°) = cosec20° sin20° + cos20° sec20° [∵Sec(90°-A)=COSECA & Cosec(90° - A) = SecA ] =sin20∘sin20∘+cos20∘cos20∘. [∵Cosec A=(1/SinA) & SecA =(1/CosA) ] = 1 + 1 = 2 |
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