(cosx+cosy)²+(sinx+siny)²=4cos²
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Answered by
1
Answer:
2sin((x+y)/2)cos((x+y)/2)
Step-by-step explanation:
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Answered by
2
Answer:
cos^2x+cos^2y+2cosx.cosy+similar terms for sin
=cos^2x+sin^2x+similar terms
=1+1+2(cosx.cosy+sinx.siny)
=2+2.cos(x-y)
=2{1+cos(x-y)}
=2{1+2cos^2(x-y)/2-1}
=2{2cos^2(x-y)/2}
=4cos^2(x-y)/2
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