Q1 of 104 Page 196

Evaluate:

sec70 sin20 — cos20 cosec70

sec(90–θ ) = cosecθ

cosec(90–θ ) = secθ


sec70 sin20 — cos20 cosec70


= sec(90–20)sin20 – cos20cosec(90–20)


= cosec20sin20 – cos20sec20



= 0


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