1.

Sec 70° Sin 20°- cos20 cosec70 = 2​

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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