In a quadrilateral ABCD, `angleA+angleD=90^(@)`. Prove that
`AC^(2)+BD^(2)=AD^(2)+BC^(2)`

In a quadrilateral ABCD,/_A+/_D=90^(@). Prove that AC^(2)+BD^(2)=AD^(2)+BC^(2)

In triangleABC , angleA= 60^(@) prove that BC^(2)= AB^(2)+AC^(2)- AB . AC

In a quadrilateral ABCD, angleB=90^(@) and AD^(2)= AB^(2) + BC^(2)+CD^(2) prove that angleACD= 90^(@) .

In Figure 2,AD perp BC. Prove that AB^(2)+CD^(2)=BD^(2)+AC^(2)

In a quadrilateral ABCD prove that AB^(2)+BC^(2)+CD^(2)+DA^(2)=AC^(2)+BD^(2)+4PQ^(2) where P and Q are middle points of diagonals AC and BD.

In a quadrilateral ABCD ,prove that AB^(2)+BC^(2)+CD^(2)+DA^(2)=AC^(2)+BD^(2)+4PQ^(2) where P and Q are middle points of diagonals AC and BD.

In the figure , ABC is triangle in which angleABClt90^(@)andADbotBC . Prove that AC^(2)=AB^(2)+BC^(2)-2BC*BD .

In a rhombus ABCD, prove that AC^(2) + BD^(2) = 4AB^(2)

In a Delta ABC , angleB is an acute-angle and AD bot BC Prove that : (i) AC^(2) = AB^(2) + BC^(2) - 2 BC xx BD (ii) AB^(2) + CD^(2) = AC^(2) + BD^(2)

In quadrilateral ABCD, AB "||" CD and AD= BC, prove that angleA=angleB.