Question

A circular plate expands when heated from a radius of 5cm to 5.06cm then the percentage increase in its area

Answer 1

area of circle = πr^2
previously ... area = 3.14 × 5 ×5 = x1
then ... area = 3.14 × 5.06 × 5.06 = x2
% increase in area = x2 - x1 × 100

do the calculations ..
hope it helps....

Answer 2

Answer:

2.29%

Step-by-step explanation:

Original radius = 5 cm

Area of plate = $\pi r^2$

                     = $3.14 \times (5)^2$

                     = $78.5 cm^2$

Now a circular plate is heated  so, new radius = 5.06 cm

So, new area  = $\pi r^2$

                     = $3.14 \times (5.06)^2$

                     = $80.3 cm^2$

So, percentage increase in area = $\frac{80.3-78.5}{78.5}\times 100$

                                                      = $2.29$

Hence the percentage increase in its area is 2.29%.