Question

15. If x = a sin 0 + b cos 0 and y = a cos 0 - b sin 0, prove that x2 + y2 = a2 + b2.
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Answer 1

Answer:

x= a sin0 + bcos0 Eqn 1

y= acoa0 - b sin0 Eqn 2

squaring and adding 1 and 2 we have,

(asin0 + bcos0)^2 + (acos0 - bsin0)^2

a^2sin^20 + 2absin0cos0 + b^2cos^20 + a^2cos^20 - 2absin0cos0 + b^2sin^20

= a^2(sin^20 + cos^20) + b^2(sin^20 + cos^20)

= a^2 + b^2

Hence proved...

Answer 2

This is the answer ok

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