Each of the base angles of a isosceles triangle is 58° and the verticles of the triangle lie on a circle. Determine the angle which the base of the triangle subtends at the centre of the circle.
-
A.
128o -
B.
16o -
C.
64o -
D.
58o
Correct Answer: Option A
Explanation
Base angle of the triangle = 58°.
The third angle = 180° – (58° + 58°)
= 64°
Angle subtended at the centre = (2 times 64° = 128°) (angle at the centre is twice the angle at the circumference).