Step 1: Draw a circle with center O and radius 4 cm.
Step 2: Draw any diameter AOB of the circle.
Step 3: At A, draw ∠OAX = 90°. Produce XA = Y.
Step 4: At B, draw ∠OBX' = 90°. Produce X B' to Y '.
Here, XAY and X BY ' are the tangents to the circle at the end points of the diameter AB.