There are two set-squares in your geometry box. What are the measures of the angles that are formed at their corners? Do they have any angle measure that is common?

Which of the following are models for perpendicular lines-

(a) The adjacent edges of a table top.

(b) The lines of a railway track.

(c) The line segments forming the letter ‘L’.

(d) The letter V.

Let be the perpendicular to the line segment. Let and intersect in the point A. What is the measure of ∠PAY?

Study the diagram. The line l is perpendicular to line m.

(a) Is CE = EG?

(b) Does PE bisect CG?

(c) Identify any two line segments for which PE is the perpendicular bisector.

(d) Are these true?

(i) AC > FG (ii) CD = GH (iii) BC < EH.

Name the types of following triangles:

(a) Triangle with lengths of sides 7 cm, 8 cm and 9 cm.

(b) Δ ABC with AB = 8.7 cm, AC = 7 cm and BC = 6 cm.

(c) Δ PQR such that PQ = QR = PR = 5 cm.

(d) Δ DEF with m ∠D = 90°.

(e) Δ XYZ with m∠Y = 90° and XY = YZ.

(f) Δ LMN with m∠L = 30°, m∠M = 70° and m∠N = 80°.