Question

If 'theta' be an acute angle and 5 cosec theta = 7 , then evaluate sin^2 theta + cos^2 theta - 1

Answer 1

We know, sin²∅ + cos²∅ = 1

××××××××××××××××××××

Sin²∅ + cos²∅ - 1

=> 1 - 1

=> 0


I hope this will help you

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Answer 2

Hey!!!

Good Afternoon

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Let thetha = A(easy for typing)

We have 5cosecA = 7

To Evaluate : sin²A + cos²A - 1

This can be done by two methods

Method 1

To Evaluate : sin²A + cos²A - 1

We know sin²A + cos²A = 1

Then = 1 - 1

=> 0 <<<<< Answer

Method 2

We have 5cosecA = 7

=> cosecA = 7/5

let opposite = 5x and hypotheus = 7x

Then by Pythagoras Theorem

=> base = √24 x

=> base = 2√6 x

Then sinA = 5/7 (reciprocal of cosecA)

Similarly cosA = 2√6x/7x(base/hypotenuse)

To Evaluate : sin²A + cos²A - 1

=> (25/49) + (24/49) - 1

=> (25 + 24 - 49)/49

=> (49 - 49)/49

=> 0/49

=> 0 <<<<<<< Answer

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Hope this helps ✌️

Use any method u feel easy