Q4 of 104 Page 196

For ΔABC, prove that (1) ,

(2)

(a) cos(90–θ ) = sinθ


tan(90–θ ) = cotθ


sin(90–θ ) = cosθ


cot(90–θ ) = tanθ


cosec(90–θ ) = secθ


sec(90–θ) = cosecθ


A + B + C = 180 (Angle sum property of triangle)


⇒ A + C = 180–B


dividing both sides by 2





(2) A + B + C = 180


⇒ B + C = 180–A


dividing by 2





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