Question

In given figure ABCD is quadrilateral in which
BC=3cm AD=13cm D C=12cm and angleABD=angle BCD=
90° Calculate the length of AB​

Answer 1

In the triangle DBC

{db }^{2}  =  {dc}^{2}  +  {bc }^{2}  

{db}^{2}  =   {12}^{2}   +  {3 }^{2}  =153.  

In triangle DBA

{ad}^{2}  =  {db}^{2}   + {ab}^{2}  

{13}^{2}  = 153 +  {ab}^{2}  

{ab}^{2}   = 169 - 153 = 16

ab =  \sqrt{16}  = 4

.'. ab=4cm