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Evaluate the following without using a table: sec⁡17°cosec73° +tan⁡68°cot⁡22° + cos 44° cosec 46° - Mathematics

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Question

Evaluate the following without using a table:

`(sec 17°)/("cosec" 73°) + (tan 68°)/(cot 22°)` + cos 44° cosec 46°

Sum
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Solution

Given:

`(sec 17°)/("cosec" 73°) + (tan 68°)/(cot 22°)` + cos 44° cosec 46°

Step 1:

Use complementary-angle identities:

73° = 90° −17° ⇒ cosec 73° = sec 17°

22° = 90° − 68° ⇒ cot 22° = tan 68°

46° = 90° − 44° ⇒ cosec 46° = sec 44°

Step 2:

`(sec 17°)/("cosec" 73°) =1`

`(tan 68°)/(cot 22° = 1)`

cos 44° ⋅ cosec 46° = cos 44° ⋅ sec 44° = 1

= 1 + 1 + 1

= 3

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Chapter 19: Trigonometry - MISCELLANEOUS EXERCISE [Page 239]

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B Nirmala Shastry Mathematics [English] Class 9 ICSE
Chapter 19 Trigonometry
MISCELLANEOUS EXERCISE | Q IV. 5. | Page 239
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