- In a circle the angle subtended at the centre is twice that of the angle subtended
at the circumference
Cut a sheet of paper in the form of a circle. Fold the paper two times to form two radii
subtending some angle at the centre. Now fold the paper again twice from the
extremities of the two radii to form another angle at the circumference of the circle.
Create a similar circle and cut off the sector alone. By folding the sector along the
radii from the midpoint of the arc and placing the folded paper on the angle formed
with circumference in the paper intact, observe that in a circle the angle subtended
at the centre is twice that of the angle subtended in the circumference.
C B
O
A
2 θ
θ
