Question

if the radius of a circle is decreased by 30%, find the percentage decrease in the area​

Answer 1

Answer:

0.51πr^2 or 51%

Step-by-step explanation:

Area of circle is given by using πr^2, where r is radius.

Suppose a circle with radius r.

Originally,

Area of circle = πr^2

When radius is decreased by 30%:

= > New radius = r - 30% of a

= > new radius = r - 0.3a = 0.7a

New area,

= > π(0.7r)^2

= > 0.49πr^2

Decrease in area:

= > πr^2 - 0.49πr^2

= > 0.51πr^2

Or,

= > 0.51 * 100%

= > 51%