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Solution: [ ]

=

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Example2: Without using trigonometric tables, evaluate cosec 89 - sec1

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Solution: Cosec89 - sec1
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= cosec(90 - 1 ) - sec1
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= sec1 - sec1
= 0

Example 3: Without using trigonometric tables evaluate

Solution:

=1
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Example 4: Express cot85 + cos75 in terms of trigonometric ratios of angles between
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0 and 45 .
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Solution: cot85 + cos75
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= cot (90 - 5 ) + cos(90 - 15 )
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= tan5 + sin15

Example 5: evaluate:

Solution:

3