Step 1:

The equation .

Square on both sides.

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Another equation is .

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Step 2:

Add equation(1) and equation(2). \ \

\ \

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Apply Pythagorean identity . \ \

Apply reciprocal identity and .

Step 3:

Multiply  and .

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Square on both sides.

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Step 4:

Subtract equation (3) from equation (4).

Solution:

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