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115
180−65.
Class 7 · Bangla Version · Mathematics
Geometry, measurement and trigonometry readiness
Use angle facts and circle measures with a stated approximation.
About this lesson and its coverage
Original Kidemy Class 7 progression. This level has its own text, examples and questions. Curriculum versions share the progression; complete board-specific coverage still needs specification matching and additional material.
Learn the idea
Angles on a straight line total 180° and around a point360°. A circle’s circumference is 2πr and its areaπr². The radius is half the diameter. State the chosen value ofπ when a numerical approximation is requested.
Worked example
With r=7 cm andπ=22/7, circumference44 cm and area 154cm².
- Identify the quantities and restrictions.
- Show a method with units or symbols.
- Check and explain the result.
Your written practice
Show your working on paper. Check your answer, then choose Next.
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44
πd=(22/7)×14.
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36
base×height.
Write in your own words. A guardian or teacher should review this response.
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π(2r)²=4πr².
Show the squared scale factor.
Write in your own words. A guardian or teacher should review this response.
Show model answer and explanation
(180−40)/2=70°.
Use the angle sum and equality.
Progress and browser storage
Notebook challenge, sources and further study
Apply the idea
Draw a circle and triangle with labelled dimensions; calculate and check their measures.
Review with a guardian or teacher
- Use the stated evidence or givens.
- Show reasoning rather than only a result.
- Review and explain one correction.
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