Explanation:
that makes ORQ a right-angled triangle, and we can use Pythagoras
c² = a² + b²
c being the Hypotenuse (the side opposite of the 90° angle), a and b are the legs.
OQ is the radius of the circle = OM = LM/2 = 20/2 = 10 cm.
RQ = PQ/2 = 16/2 = 8 cm.
so, our Pythagoras equation looks like :
OQ² = RQ² + OR²
10² = 8² + OR²
100 = 64 + OR²
36 = OR²
OR = 6 cm
RM = OM - OR = 10 - 6 = 4 cm