An arc of length 6cm subtending an angle at the centre of 1.5c is equivalent to the whole circle of length 2πr subtending 2π radians. Therefore,

6/1.5 = 2πr/2π = r : Then r = 4 cm.

NOTE : A radian can be defined as the angle at the centre of a circle subtended by an arc equal in length to the radius. So an arc subtending an angle of 2 radians is twice the length of the radius. An arc subtending an angle of 1.5 radians is thus 11/2 times as long as the radius.

Subtending

flowers having a small leafy or scaly structure subtending a flower in its axil E.g. bougainvillea

An angle of 180 degrees has no name, but its subtending lines would form one straight line.

If this is a central angle, the 72/360 x (2xpix4) = 5.024