Area of circles
Grade 7 students in Big Ideas Math Advanced 2 (Chapter 13: Circles and Area) learn the area formula for circles: A = pi r squared, where r is the radius. Students use pi approx 3.14 for approximate answers or leave pi as a symbol for exact answers, and apply the formula to composite figures containing circular regions.
Key Concepts
For a circle with radius $r$: The area is $A = \pi r^2$. The number $\pi$ (pi) is a constant used for all circles. For exact answers, leave the symbol $\pi$ in the solution. For approximate answers, use $\pi \approx 3.14$ or $\pi \approx \frac{22}{7}$.
Common Questions
What is the formula for the area of a circle in 7th grade?
The area of a circle is A = pi times r squared, where r is the radius. Use pi approx 3.14 for approximate decimal answers, or keep pi for exact answers.
How do you find the area of a circle if you know the diameter?
Divide the diameter by 2 to find the radius, then apply A = pi r squared. For a circle with diameter 20 feet, radius = 10 and area = pi times 100 = 100pi square feet.
When should you use 22/7 instead of 3.14 for pi?
Use 22/7 when the radius is a fraction with denominator divisible by 7, as it simplifies the arithmetic. For most problems, use 3.14.
What chapter in Big Ideas Math Advanced 2 covers area of circles?
Chapter 13: Circles and Area in Big Ideas Math Advanced 2 (Grade 7) covers the area of circles formula.
What units are used for circle area?
Area is always in square units such as cm squared, ft squared, or m squared.