Question

which formula is used to calculate the area of a circle, an essential part of calculating the surface area for circular faces?
a. ( a=\frac{1}{2} b h )
b. ( a=l w )
c. ( a=2 pi r h )
d. ( a=pi r^{2} )

Explanation:

Step1: Analyze each option

• Option a: \(A = \frac{1}{2}bh\) is the formula for the area of a triangle, where \(b\) is the base and \(h\) is the height.
• Option b: \(A=lw\) is the formula for the area of a rectangle, where \(l\) is the length and \(w\) is the width.
• Option c: \(A = 2\pi rh\) is the formula for the lateral (curved) surface area of a cylinder, where \(r\) is the radius of the base and \(h\) is the height of the cylinder.
• Option d: \(A=\pi r^{2}\) is the formula for the area of a circle, where \(r\) is the radius of the circle.

Answer:

d. \(A=\pi r^{2}\)