First find the radius by taking half the diameter. Use the radius to find the base area by using the formula for the area of a circle. Find the product of the base area and height, and then take one-third of the product.
Divide the sides of the larger triangle by the corresponding side of the smaller one:
18/7.2 = 2.5
Figure A is 2.5 times the size of figure B
The scale factor is 2.5
