Step 1: Draw a isosceles triangle ABC with AB = 8 cm, and altitude = 4 cm

Skill 1:Draw a line segment measuring one of the given base length

of the triangle..

Skill 2: Draw two intersecting arcs at 4 cm distance from points A and B

on either side of AB.

Skill 3: Now join these arcs to get perpendicular bisector CD of AB.

Skill 4: Join A and B to C to get the triangle ABC.

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Step 2: Draw any ray DX making an acute angle with poin D

Step 3: Locate 3 points D_1, D_2, \text{ and } D_3 . on DX

NOTE: such that DD_1=D_1D_2=D_2D_3

Step 4: Join D_2 to point B

NOTE: 1 \frac{1}{2} = \frac{3}{2} times of the corresponding sides.

Step 5: Draw a line from D_3 parallel to D_2B so that it meets the extension of AB at B_1

Step 6: Again draw B_1 C_1 parallel to BC

Step 7: Draw A_1 C_1 parallel to AC

So triangle A_1B_1C_1 is the required triangle.