How do you solve?

Question

A side of an equilateral triangle is measured to be 10 cm. Estimate the change in the area of the triangle when the side shrinks to 9.8 cm.

Answer 1

Estimate based on reduction of side length by 2%, i.e. length multiplied by 0.98; area is reduced by factor 0.98² which equals 0.9604, about 4% reduction.