# CBSE Class 10-Mathematics: Chapter –12 Areas Related to Circles Part 3

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**Question 17:**

The radius of a circle is , then the area of the circle is

(a)

(b)

(c)

(d)

**Answer:**

(d)

**Question 18:**

Area of a sector of angle of a circle with radius is

(a)

(b)

(c)

(d)

**Answer:**

(a)

**Question 19:**

The diameter of a circle whose area is equal to the sum of the area of the two circles of radii and is

(a)

(b)

(c)

(d)

**Answer:**

(a)

**Question 20:**

The circumference a circle is . Then its area is

(a)

(b)

(c)

(d)

**Answer:**

(a)

## 2 Mark Questions

**Question 1:**

The radii of two circles are and respectively. Find the radius of the circle having area equal to the sum of the areas of the two circles.

**Answer:**

Let R be the radius of the circle which has area equal to the sum of areas of the two circles, then

According to the question,