Question

calculate the area of the circle. formula: ( a=pi r^{2} ) use 3.14 for pi. ( a=? mathrm{cm}^{2} ) round to the nearest tenth.

Explanation:

Step1: Substitute the radius into the formula

Given \( r = 5\) cm and \( \pi=3.14\), the formula for the area of a circle is \( A=\pi r^{2}\). Substitute \( r = 5\) into the formula: \( A = 3.14\times5^{2}\).

Step2: Calculate \(5^{2}\)

\(5^{2}=5\times5 = 25\). So the formula becomes \( A=3.14\times25\).

Step3: Perform the multiplication

\(3.14\times25=(3 + 0.14)\times25=3\times25+0.14\times25=75 + 3.5=78.5\).

Answer:

\(78.5\)