A parallelogram containing a `60^0` angle has perimeter `p` and its longer diagonal is of length `ddot` Find its area.

Explanation

Perimeter=`2(x+y)=P`

`x+y=P/2-(1)`

`In/_ABD`

`d^2=y^2sin^2 60+(x+ycos60)^2`

`d^2=y^2sin^2 60+x^2+y^2cos^2 60+2xycos60`

`d^2=x^2+y^2+2xy*1/2`

`d^2=x^2+y^2+xy`

`d^2=(x+y)^2-xy`

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