In ΔABC, a perpendicular AD is drawn to BC. If BD= 8 cm, DC = 2 cm and AD= 4 cm, then ___.
Using Pythagoras' theorem in ΔADC,AC2=AD2+DC2.AC2=42+22=20 AC=√20cm − − − −(1)Similarly, in ΔADBAB2=AD2+BD2 =42+82=80. AB=√80cm=2√20cm − − − −(2) =2×AC (Using (2))