1. Draw line PE=4cm using scale
2. At point P , taking P as center draw arc of radius 3cm
3. Draw a arc of radius 5cm taking E as center.Let both arc intersect at point N.
4. Join line EN and NP using scale .
If the circles are drawn they will intersect at another point bellow
line PE.You will get congruent triangle. This is true for all triangles.