A circle has a diameter of \(14\) cm. What is its radius?
- A \(7\) cm
- B \(14\) cm
- C \(21\) cm
- D \(28\) cm
Check answer and explanation
Answer A: \(7\) cm
The radius is half the diameter: \(14\div2=7\) cm.
CH07-01 lesson
Parts of a Circle Learning Activity
A focused Grade 7 learning session for Parts of a Circle using visual models, worked examples, strategy guidance, and a short mastery check.
- 15
- minutes
- 6
- lesson parts
- 11
- practice items
Students will build Grade 7 mastery of parts of a circle using models, equations, and test-style reasoning.
Student goal: I can solve problems involving parts of a circle.
Learn the Idea
Parts of a Circle is part of Grade 7 Measurement Geometry. This activity focuses on the central idea students need before they move into independent practice.
Students will build Grade 7 mastery of parts of a circle using models, equations, and test-style reasoning.
See the Math
| What to notice | How to use it |
|---|---|
| Numbers, units, labels, diagrams, or graphs | Identify what each part represents before calculating. |
| The relationship in the problem | Connect the model to an equation, comparison, or explanation. |
Use the figures and worked questions in the practice set below as the visual model for this skill.
Follow a Worked Example
Read the first practice question slowly. Decide what the question is asking, choose a strategy, solve, and then compare your reasoning with the answer explanation.
For Parts of a Circle, a strong worked example should show the setup, the calculation or model, and a final answer that matches the context.
Connect It to a Real Situation
Many Grade 7 test questions use real situations. Look for quantities, units, rates, measures, expressions, or data values that connect the math to the story.
After solving, explain what the answer means in the situation, not just the number you calculated.
Avoid Mistakes and Choose a Strategy
- Underline the exact question before solving.
- Label units, variables, or graph axes when they appear.
- Estimate first so unreasonable answers are easier to catch.
- Review missed questions and write the reason for each mistake.
Remember the Key Idea
I can solve problems involving parts of a circle.
Use the warmup, guided question, practice set, and exit questions below to check whether this skill is ready or needs more practice.
Solve before opening the answer
Use scratch paper. The explanation matters more than simply seeing whether the choice is correct.
warmup
2 questionsThe diagram below shows a circle with center \(O\). Which line segment is the radius of the circle?
- A \(OP\)
- B \(OQ\)
- C \(PQ\)
- D \(QP\)
Check answer and explanation
Answer A: \(OP\)
The radius is any segment from the center to the circle. \(OP\) is labeled and is a radius.
guided
1 questionA circle has a radius of \(5\) inches. What is its diameter?
- A \(2.5\) inches
- B \(5\) inches
- C \(10\) inches
- D \(15\) inches
Check answer and explanation
Answer C: \(10\) inches
Diameter is twice the radius: \(2 \times 5 = 10\) inches.
practice
5 questionsIn the circle below, which line segment is a chord?
- A \(\ell_1\) (segment \(AB\))
- B \(\ell_2\) (segment \(OC\))
- C Segment \(OA\)
- D None of the above
Check answer and explanation
Answer A: \(\ell_1\) (segment \(AB\))
A chord connects two points on the circle. \(AB\) is a chord. \(OC\) is a radius, not a chord.
Which point is the center of the circle?
- A \(N\)
- B \(M\)
- C \(P\)
- D \(Q\)
Check answer and explanation
Answer B: \(M\)
The center is the point inside the circle equidistant from all points on the circle. \(M\) is at the center.
A circle has a diameter of \(\frac{30}{7}\) meters. What is its radius?
- A \(\frac{15}{7}\) meters
- B \(\frac{30}{7}\) meters
- C \(\frac{60}{7}\) meters
- D \(7\) meters
Check answer and explanation
Answer A: \(\frac{15}{7}\) meters
\(r = \frac{d}{2} = \frac{30}{7} \div 2 = \frac{30}{14} = \frac{15}{7}\) meters.
In the circle below, which of the following is an arc?
- A The segment \(OA\)
- B The curve from \(A\) to \(C\)
- C The chord \(AC\)
- D The point \(O\)
Check answer and explanation
Answer B: The curve from \(A\) to \(C\)
An arc is a part of the circle's circumference. The curve from \(A\) to \(C\) is an arc.
If the radius of a circle is \(12\) units, how many times larger is the diameter than the radius?
- A \(1\) time
- B \(2\) times
- C \(3\) times
- D \(4\) times
Check answer and explanation
Answer B: \(2\) times
The diameter is always \(2\) times the radius: \(d = 2r\).
exit
3 questionsIn the circle below, which region is a sector?
- A The arc \(AB\)
- B The region bounded by \(OA\), arc \(AB\), and \(OB\)
- C The chord \(AB\)
- D The center \(O\)
Check answer and explanation
Answer B: The region bounded by \(OA\), arc \(AB\), and \(OB\)
A sector is a pie-shaped region formed by two radii and the arc between them.
Which is the best approximation for \(\pi\)?
- A \(\frac{22}{7}\)
- B \(3\)
- C \(2.5\)
- D \(4\)
Check answer and explanation
Answer A: \(\frac{22}{7}\)
\(\pi \approx 3.14159\ldots\). The common approximations are \(3.14\) and \(\frac{22}{7} \approx 3.142857\).
Every diameter of a circle is also a:
- A Radius
- B Sector
- C Chord
- D Arc
Check answer and explanation
Answer C: Chord
A diameter is a chord that passes through the center. All diameters are chords.
