The formula for the area of a circle can be found by using a parallelogram. explain the way to derive the formula.

the base of the parallelogram, b = half of the circumference of the circle.

half of the circumference of the circle =  πr

therefore, b =  πr

the height of parallelogram, h  =  the radius of the circle

therefore, h = r

area of  a parallelogram = bh

to find the area of the circle, let's substitute  πr  for b and r for h  in the above formula.

area of the circle =  πr * r

area of the circle =  πr²hence, the formula to find area of a circle is  πr²

answer: city needs 2.4 inches of rainfall more to match the record of 40 inches.

step-by-step explanation:

since we have given that

total annual rainfall a city record = 40 inches

this year, total rainfall recorded = 37.6 inches

number of inches of rainfall   is needed to match the record of 40 inches is given by

hence, city needs 2.4 inches of rainfall more to match the record of 40 inches.