Draw a circle of radius 4 cm and mark its centre as O.
Mark a point P outside the circle such that OP is 7 cm.
Join OP.
Bisect OP at C.
Taking C as centre and OC as the radius draw a circle which intersects the previous circle at T and T’.
Join PT and PT’ which are the required tangents. Measure PT and PT’. It will be equal to 5.7 cm (approx.)
Alternate Method -
Since OT is perpendicular to TP
We can use Pythagoras Theorem, In △OTP
PT2=72−42
PT = √33 = 5.7 (approx)