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If A and B are complementary angles, prove that: cosec2 A + cosec2 B = cosec2 A cosec2 B - Mathematics

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Question

If A and B are complementary angles, prove that:

cosec2 A + cosec2 B = cosec2 A cosec2 B

Sum

Solution

Since, A and B are complementary angles, A + B = 90°

cosec2 A + cosec2 B

= cosec2 A + cosec2 (90° – A)

= cosec2 A + sec2 A

= `1/sin^2A+1/cos^2A`

= `(cos^2A + sin^2A)/(sin^2Acos^2A)`

= `1/(sin^2Acos^2A)`

= cosec2 A sec2 A

= cosec2 A sec2 (90° – B)

= cosec2 A cosec2 B

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Chapter 21: Trigonometrical Identities - Exercise 21 (E) [Page 332]

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Selina Mathematics [English] Class 10 ICSE
Chapter 21 Trigonometrical Identities
Exercise 21 (E) | Q 9.3 | Page 332
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