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Question
Find the value of angle A, where 0° ≤ A ≤ 90°.
cos (90° – A) . sec 77° = 1
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Solution
cos (90° – A) . sec 77° = 1
`sinA. 1/(cos77^circ) = 1`
sin A = cos 77°
= cos (90° – 13°)
= sin 13°
A = 13°
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