Question

solve this question This question is of Trigonometry chapter
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Answer 1

Solution:-

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4 Cos A = 3

Cos A = 3/4

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We know that the formula of Cos = Base/Height

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If we compare both statements we get to know that Base = 3 and Height = 4

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Formula of Cosec = Height/Perpendicular

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We know height but not perpendicular so now we find perpendicular by using PGT( Pythagoras Theorem)

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By Pythagoras Theorem

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Perpendicular(P)² = (Height)² - (Base)²

Perpendicular(P)² = (4)² - (3)²

Perpendicular(P)² = 16 - 9

Perpendicular(P)² = 7

Perpendicular(P) = √7

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First, find Cosec

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Cosec = Height/Perpendicular

Cosec = 4/√7

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Now, find Cosec² A - 4

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= (4/√7)² - 4

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Square root cancelled out

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= 16/7 - 4

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Same the denominator

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= 16/7 - 28/7

= 12/7