- #1

ViresArcanum

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## Homework Statement

Given is a parallelogram which has diagonals of the length 7 (e) and 9 units (f). How big is its circumference?

The sides are a,b,c,d; a being the bottom side, rest is anti-clockwise... alpha is the angle of a etc...

## Homework Equations

no are given, i guess pythagoras or trig might be useful.

diagonals of a parallelogram (might be useful)

e=sqrt(a^2+d^2+2*a*d*cos(alpha))

f=sqrt (a^2+d^2-2*a*d*cos(alpha))

alpha=gamma

beta=delta

beta=180-alpha

## The Attempt at a Solution

I tried using this first of all by drawing lots of triangles in the parallelogram and solve it with pythagoras or trig functions but without success

afterwards i tried using the formulas for the diagonals but without knowing a and d i didn't have much of a success either