Draw a line XY. Take any point D on this line. Construct perpendicular PD

on XY. Cut a line segment AD from D equal to 3.5 cm.

Make angles

equal to 30° at A

on both sides of

AD, say ∠CAD

and ∠BAD where

B and C lie on XY.

Then ABC is the

required triangle.

**Justification**

Since ∠A = 30° +

30° = 60° and

AD ⊥BC, ΔABC

is an equilateral

triangle with

altitude AD =

3.5 cm.