Answer: AD = 9cm
Step-by-step explanation: This is a 30-60-90 triangle, so the hypotenuse is equal to twice the length of the short side of the right angle.
BC is the short side of the large triangle, so AB, the hypotenuse of the large triangle is 2×6, 12 cm
BC is also the hypotenuse of the small triangle, ΔBCD, so it is twice the length of BD, to that makes BD = 6/2= 3
Subtract BD from AB.
That's 12 - 3 = 9 the length of AD
