Question

estimate values of expressions with pi quick check
what is the area of a circle with a diameter of 10 millimeters? estimate the area to the tenths place using 3.14 for π. (1 point)
15.7 square mm
78.5 square mm
314 square mm
79 square mm

Explanation:

Step1: Find the radius

The radius \(r\) of a circle is half of the diameter \(d\). Given \(d = 10\) mm, so \(r=\frac{d}{2}=\frac{10}{2}=5\) mm.

Step2: Use the area formula

The area formula of a circle is \(A=\pi r^{2}\). Substitute \(r = 5\) mm and \(\pi=3.14\) into the formula. Then \(A = 3.14\times5^{2}\).

Step3: Calculate \(5^{2}\)

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

Step4: Multiply

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

Answer:

78.5 square mm