Draw a base line BC = 7cm
Make an angle using compass of 75 degree at Point b
Den extend the line to 13cm
Join the line from 13cm to c
Draw a perpendicular bisector of the line
The point where the line intersects the line b
Mark it as a
Join ba and ac
Therefore Abc is required triangle
1) draw a line segment bc 7cm
2) with b as centre construct 75 degree
3) With Center B and radius 13cm, make an arc which intersects BX at D. 
4) join DA
5)draw th perpendicular bisector of AD
it intersect the line segment BD at point C. 
6)join CA
7)ABC is the required triangle