D1=8cm
D2=15cm
Therefore, divide the D1 and D2 in two equal halves.
Then we will get 4 right angled triangle.
The base of each triangle would be D1/2=8/2=4cm.
And the perpendicular would be D2/2=15/2=7.5cm.
Now we will find the hypotenuse of each ∆.
Triangle 1= Hypotenuse^2=Perpendicular ^2+Base^2.
H^2= 8^2+7.5^2
H^2=64+56.25
H ^2=120.25
H= √120.25