Relationship Between Radius and Diameter
Relationship Between Radius and Diameter is a Grade 7 math skill in Illustrative Mathematics, Chapter 3: Measuring Circles. Students learn that a circle diameter is always twice the radius (d=2r) and apply this relationship to solve problems involving circle measurements.
Key Concepts
The diameter ($d$) of a circle is twice its radius ($r$). The radius is half of the diameter.
$$d = 2r$$ $$r = \frac{d}{2}$$.
Common Questions
What is the relationship between radius and diameter?
The diameter of a circle is always exactly twice the radius: d equals 2r. Equivalently, the radius is half the diameter: r equals d divided by 2.
How do you find the diameter if you know the radius?
Multiply the radius by 2. For example, if the radius is 7 cm, the diameter is 7 times 2 equals 14 cm.
How do you find the radius if you know the diameter?
Divide the diameter by 2. For example, if the diameter is 20 inches, the radius is 20 divided by 2 equals 10 inches.
Why is understanding radius and diameter important in Grade 7?
Radius and diameter are fundamental measurements used to calculate circumference (C equals pi times d) and area (A equals pi times r squared) of circles.
What chapter covers radius and diameter in Illustrative Mathematics Grade 7?
The relationship between radius and diameter is covered in Chapter 3: Measuring Circles in Illustrative Mathematics Grade 7.