QQuestion
Using ruler and compass, construct △ABC where AB = 6 cm, AC = 4.5 cm and ∠BAC = 120°. Construct the circle circumscribing △ABC. Measure and write the radius of the circle.
✓Answer
Given, AB = 6 cm, AC = 4.5 cm and ∠BAC = 120°
Steps of construction,
1. Draw AB = 6 cm.
2. At A, construct ∠BAY = 120°.
3. With A as centre and radius 4.5 cm, draw an arc cutting AY at C.
4. Join B to C to obtain △ABC.
5. Construct the perpendicular bisectors of AB and AC.
6. Mark their point of intersection as O. This is the circumcentre.
7. With O as centre and OA as radius, draw a circle through A, B and C.
8. Measure OA or OC.
The measured radius is approximately 5.2 cm.
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