Thursday , July 7 2022
Mathematics

NCERT 5th Class (CBSE) Mathematics: Polygons And Circles

QUADRILATERALS

Quadrilaterals are four sided polygons. Here are some special quadrilaterals.
Quadrilaterals-0-1

Quadrilaterals-1

Quadrilaterals-2

Angles of Quadrilaterals

Look at these quadrilaterals.

Angles of Quadrilaterals-1-1

Each has a diagonal that divides the quadrilateral into two triangles.

We know that the sum of angles in a triangles is 180°.

Angles of Quadrilaterals-2

Since each quadrilateral has two triangles, the sum of angles in the quadrilateral = 180° × 2 = 30°.

Square ABCD has ∠A = ∠B = ∠C = ∠D = 90°

Sum of the angles in Δ ABD = 180° (90° + 45° + 45°)

Sum of the angles in ΔBCD = 180° (90° + 45° + 45°)

Sum of the angles in ΔABD + Sum of the angles ΔBCD = 360°

Sum of the angles in square ABCD =360°

You can check this out for yourself.

1. Draw and cut out a quadrilateral.

Angles of Quadrilaterals-3

If you know the measure of three angles of a quadrilateral, you can find the fourth angle.

Angles of Quadrilaterals-4

∠a + ∠b + ∠c = 50 + 80 + 120 = 250°

∠d = 360 – 250 = 110°

Check Also

5th class NCERT Hindi Book Rimjhim

चुनौती हिमालय की 5th NCERT CBSE Hindi Rimjhim Ch 18

चुनौती हिमालय की 5th Class NCERT CBSE Hindi Book Rimjhim Chapter 18 प्रश्न: लद्दाख जम्मू-कश्मीर राज्य में …