Question

If cos theta =21/20 then find cot theta and cosec theta

Answer 1

Solution:

I am using A instead of theta.

cos A = 21/20

=> secA = 20/21

We know that,

tan² A = sec² A - 1

= (21/20)²-1

= (441/400) - 1

= (441 - 400)/400

= 41/400

tanA = √(41/400)

=> tan = (√41)/20

=> cotA = 20/√(41) ----(1)

Now ,

cosec² A = 1 + cot²A

= 1 + (20/√41)²

=1 + 400/41

= (41+400)/41

= 441/41

cosecA = √(441/41)

= 21/√41----(2)

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