Question

8 cm6cm 8cm0Fig. 12.5Fig. 12.6Fig. 12:6 shows two concentric circles withcentre O and radius 7 and R respectively.If R =3r, express the area of the shadedpart in terms of 77 and r.

Answer 1

In this case, we'll have to carry out several steps to find the solution.

Step 01:

Data:

ring:

R = 3r

Step 02:

geometry:

shaded area:

we must analyze the figure to find the solution.

A = πR² - πr²

A = π(3r)² - πr² = π (9r² - r²) = π (8r²)

The answer is:

A = π (8r²)