NCERT Exemplar Solutions
Class 10 - Mathematics - CHAPTER 11: Area Related To Circles - Exercise 11.1
Question 1

Question.  1

If the sum of the areas of two circles with radii \(R_1\) and \(R_2\) is equal to the area of a circle of radius \(R\), then

(A)

\(R_1 + R_2 = R\)

(B)

\(R_1^2 + R_2^2 = R^2\)

(C)

\(R_1 + R_2 < R\)

(D)

\(R_1^2 + R_2^2 < R^2\)

Detailed Answer with Explanation:

Step 1: Recall the formula for the area of a circle.
Area of a circle = \(\pi r^2\), where \(r\) is the radius.

Step 2: Find the area of the first circle.
Radius = \(R_1\). So, Area = \(\pi R_1^2\).

Step 3: Find the area of the second circle.
Radius = \(R_2\). So, Area = \(\pi R_2^2\).

Step 4: Add the two areas.
Total area = \(\pi R_1^2 + \pi R_2^2\).

Step 5: According to the question, this total area is equal to the area of a bigger circle with radius \(R\).
Area of bigger circle = \(\pi R^2\).

Step 6: Write the equation.
\(\pi R_1^2 + \pi R_2^2 = \pi R^2\).

Step 7: Cancel \(\pi\) from both sides (since it is common and non-zero).
\(R_1^2 + R_2^2 = R^2\).

Final Answer: The correct option is (B).

NCERT Exemplar Solutions Class 10 – Mathematics – CHAPTER 11: Area Related To Circles – Exercise 11.1 | Detailed Answers