Area of the red part?
A normal-level "Area" problem.With scattered sectors, add up the central angles first. 360° means one whole circle, 180° a semicircle. Computing them one by one is the last resort.
GivenA 10 cm square with a quarter circle of radius 5 cm drawn at each corner / π = 3.14
Hints
- The four white pieces are all quarter circles centred on the square's corners, and all four have the same radius.
- Four lots of 90° make 360° — so the four pieces together are exactly one whole circle. There is no need to work them out one at a time.
- Here is that circle, gathered in the middle. Its radius is 10 ÷ 2 = 5 cm, so its area is 5 × 5 × 3.14 = 78.5 cm².
- The square is 10 × 10 = 100 cm². Take away the circle: 100 − 78.5
Answer 21.5cm²
More "Area" problems
- Area of the inner triangle?
- Area of triangle DOA?
- Area of quadrilateral ABCD?
- Area of the overlap?
- Total area of the two crescents?
- Area swept by the square?
Browse by idea
- Add, then subtract — an overlap is a counting problem
- Circles and sectors — multiply by π once, at the very end