Revisions
Grade 10
Grade 11
Angles in a Circle
Grade
10
Term
3
Foundation Level (Fail → Pass)
State the "Angle at the Centre" theorem. If the angle at the centre is 100°, what is the angle at the circumference?
State the "Angles in the Same Segment" theorem. Draw a diagram to illustrate it.
State the "Angle in a Semicircle" theorem.
If AB is the diameter of a circle and C is a point on the circumference, what is the value of ∠ACB?
In a circle with centre O, points A, B, and C are on the circumference. If ∠AOB = 80°, find ∠ACB.
Intermediate Level (Pass → Credit)
6. Create a study guide with a problem-solving checklist for Angles in a Circle: 1. Look for a diameter, 2. Look for the centre, 3. Look for a bow-tie shape, 4. Use other geometry.
7. In a circle, a chord AB subtends an angle of 40° at a point X on the circumference. If Y is another point on the same arc, what is ∠AYB?
8. A, B, C, D are points on a circle. AC and BD are diameters. If ∠CAD = 30°, find the value of ∠ACB.
9. In a circle with centre O, if triangle AOB is an equilateral triangle, find the value of angle ACB.
10. Prove that opposite angles of a cyclic quadrilateral are supplementary (add up to 180°).
Advanced Level (Credit → Distinction)
11. Give me a rider problem that combines the "Angle at the Centre" theorem with the properties of isosceles triangles (formed by two radii).
12. Two circles intersect at P and Q. A straight line APB is drawn to meet the circles at A and B. Another straight line CQD is drawn to meet the circles at C and D. Prove that AC is parallel to BD.
13. Give me a challenging rider problem that requires using all three circle theorems to find a final angle.
14. PQ is a diameter of a circle. The chord RS is produced to X. Prove that ∠PSX + ∠QRX = 180°.
15. In triangle ABC, the bisector of ∠A meets the circumcircle of the triangle at X. Prove that XB = XC.
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Idasara Academy ඉගෙනුම් සම්පත් නිර්මාණය කර ඇත්තේ සිසුන්ට මගපෙන්වීම, පුහුණුව සහ අධ්යයන උපායමාර්ග ලබාදී සහයෝගය දැක්වීමටය.
කෙසේ වෙතත්, සියලුම විභාග සහ නිල අවශ්යතා සඳහා, සිසුන් අනිවාර්යයෙන්ම ශ්රී ලංකා අධ්යාපන අමාත්යාංශයේ, අධ්යාපන ප්රකාශන දෙපාර්තමේන්තුව විසින් ප්රකාශයට පත් කරන ලද නිල පෙළපොත් සහ සම්පත් පරිශීලනය කළ යුතුය.
ජාතික විභාග සඳහා අන්තර්ගතයේ නිල බලය ලත් මූලාශ්රය වනුයේ රජය විසින් නිකුත් කරනු ලබන මෙම ප්රකාශනයි.
