State and prove the Pythagoras theorm

1.	State and prove the Pythagoras theorm
Answer» Phythagoras th. - In a right ∆ the square of hypo. is equal to sum of squares of other 2 sides.Construct a ∆ABC in which D is perpendicular to AC.∆ADB~∆ABC (By AA similarity) ----(1)Similarly ∆BDC~ABC∆ ------(2)Now; AD/AB=AB/AC (from 1)So by cross multiplying AB2=AD×AC-----(3)Next; DC/BC=BC/AC (from 2)Again by cross multiplying BC2= AC×DC-----(4)Now from adding (3) and (4) we have;AB2+BC2=(AD×AC)+(AC×DC)AB2+BC2= AC(AD×DC)AB2+BC2=AC×ACAB2+ BC2= AC2 {Hence Proved} You can get this theorm in ncert book just open the book and see See from ncert

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