Hard
A point P is at a distance of 82 cm from the centre O of a circle of radius 18 cm. Find the length of the tangent drawn from P to the circle.
Explanation
Explanation
The tangent, the radius to the point of contact, and the line OP form a right triangle with OP as the hypotenuse. By Pythagoras: (tangent)² = OP² - r² = 82² - 18² = 6724 - 324 = 6400. So tangent length = √6400 = 80 cm.
PRO TIP
Re-check your working by substituting the answer back into the original question.