← CBSE Class 10 (age 15) Mathematics ยท Areas Related to Circles

Combinations of Plane Figures

Practice Quiz

Q1. What is the radius if diameter is 10?

โœ” Radius is half of diameter.

Q2. Area of circle formula?

โœ” Standard area formula for a circle.

Q3. How to find shaded area?

โœ” Often involves subtraction of non-shaded parts.
Show transcript
[Slide 1] Visualizing Combined Shapes
Many real-world designs combine circles, triangles, and rectangles. To find the total area, we break these complex shapes into simpler known figures. Then we add or subtract their individual areas based on the design.

[Slide 2] Method to Solve Problems
First, identify the basic shapes like sectors, triangles, or semicircles within the figure. Calculate the area of each component using standard formulas. Finally, combine these values by adding or subtracting as required by the shaded region.

[Slide 3] Example: Square with Semicircles
Consider a square with side length fourteen centimeters. Semicircles are drawn outwardly on each side of this square. We need to find the total area covered by these semicircles and the square.

[Slide 4] Calculating Total Area
The square area is fourteen squared, which equals one hundred ninety-six. Four semicircles of radius seven make two full circles. Adding the circle areas to the square gives the final total area.

[Slide 5] Avoid This Common Error
Students often mistake the side length for the radius of the semicircles. Remember that the diameter equals the side, so the radius is half. Also, ensure you are calculating only the shaded portion requested.

[Slide 6] Key Takeaways Summary
To master combinations of plane figures, split them into basic shapes like circles and polygons. Apply the correct area formula for each part accurately. Always double-check your calculations and units before finalizing your answer.