Question

Draw an equilateral triangle of side 4.5 cm and draw its circumscribed circle. Find the radius of the circle. [3 marks]

Answer 1

Steps of construction:

i) Draw a line segment BC = 4.5 cm

ii) With centers B and C,draw two arcs of radius 4.5 cm which intersect each other at A. [ 1 mark]

iii) Join AC and AB.

iv) Draw the perpendicular bisectors of AC and BC intersecting each other at O. [ 1 mark]

v) With O as centre, and radius equal to OA (or OB or OC) draw a circle which will pass through A, B and C. This is the required circumcircle for the triangle ABC.

vi) Measure radius. OA = 2.6 cm [ 1 mark]