In ΔABC is the bisector of ∠A meeting BC at D. If AC = 21 cm, BC = 11 cm and the length of BD is 3 cm less than DC, then the length(in cm) of side AB is:
Answer & explanation
Correct answer: option 4
Let the length of CD be x
= x + 3 - 3 = 11
= 2x - 3 = 11
= 2x = 14
= x = 7
Length of BD = 7 - 3 = 4
From angle bisector property
\(\frac{AB}{4}\) = \(\frac{21}{7}\)
= AB = 4 x 3
= 12 cm.
Therefore, length of AB is 12 cm.