Question

If cot A + cosec A = and A is an acute angle, then the value of cos A is??
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Answer 1

Answer:

Here, cot A + cosec A = 3

= cosA/sinA + 1/sinA = 3

= cosA + 1 = 3 sinA

Squaring both sides.

⇒ (cos A + 1)2 = 9sin2 A

⇒ cos2 A + 2cos A + 1 = 9 (1 – cos2 A)

⇒ 10 cos2A + 2 cos A – 8 = 0

⇒ 5 cos2 A + cosA – 4 = 0

⇒ (5 cos A – 4)(cos A + 1) = 0

(∵ A is an acute angle)

cosA = 4/5.

Step-by-step explanation:

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