4. Construct ΔABC such that AB = 2.5 cm, BC = 6 cm and AC = 6.5 cm. Measure ∠B.
Step 1. Draw a line segment BC = 6 cm.
Step 2. With B as a center and radius 2.5 cm, draw an arc outside.
Step 3. With C as a center and radius 6.5 cm, draw another arc, cutting the previous arc at A.
Step 4. Join AB and AC.
Now, ΔABC is the required triangle.
Now, when we measure the angle B by the protector then we find that angle B is 90o