Q9 of 104 Page 196

If sec2A = cosec(A — 42), where 2A is the measure of an acute angle, find the value of A.

sec(90–θ) = cosecθ


sec2A = cosec(A–42)


∴ sec2A = sec(90–(A–42))


⇒ 2A = 90 – A + 42


⇒ A = 44


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