Have to use pythagoras theorem

Question

In parallelogram ABCD, the diagonals AC is at right angles to AB.If AB=12 & AC=13. I have to find the area of parallelogram. How can I use Pythagoras theorem here? I do not understand.

Answer 1

The area of a parallogram is the product of base and height. In your case, the base is AB and the height is AC, so the area is just $12\cdot13=156$, so no need of Pythagoras' theorem. You can use it, however, to calculate $BC=\sqrt{AB^2+AC^2}$.

Answer 2

As sranthrop says, there is no need to use Pythagoras thm.

Try solving this one :

In parallelogram ABCD, the diagonals AC is at right angles to DB.If AB=12 & AC=13. Find the area of parallelogram, using Pythagoras theorem. (Rhombus).

Typo in your exercise?