Thus, the value of x is 50
Problem 6. Explain how this figure is a trapezium. Which of its two sides are parallel? [NCERT)
M
100
Answers
Answer:
Mathematics NCERT Grade 8, Chapter 3: Understanding Quadrilaterals- Different varieties of curves have already been discussed in earlier classes. Starting with polygons chapter moves to the topic- classification of polygons.
Difference between polygon curves and non-polygon curves is explained with the help of a diagram.
Polygons are classified according to the number of sides (or vertices). Classification is explained with the help of suitable figures in the table listed in section 3.2.1. Students must understand this concept and remember the classifications given.
A diagonal is a line segment connecting two non-consecutive vertices of a polygon.
After that Convex and concave polygon are discussed. Before moving to angle sum property students will learn about regular and irregular polygons.
A regular polygon is both equiangular and equilateral.
A rectangle is equiangular but not equilateral.
A square has sides of equal length and angles of equal measure that's why it is considered as a regular polygon.
Talking about angle sum property; Angle sum property states that the sum of measures of the three angles of a triangle is 180°.
After going through the introductory section students about the above discussed topics need to solve the problems of exercise 3.1.
Sum of the measure of the exterior angles of a polygon is another topic that will be discussed in this chapter.
The sum of the measures of the external angles of any polygon is 360°.
Various kinds of quadrilaterals are explained like trapezium, parallelogram, etc. Point to be noted that kite is also a special type of quadrilateral. Angles of parallelogram and some special parallelograms are also discussed.
The opposite angles of a parallelogram are of equal measure.
A short note about diagonal of parallelogram is given that in general, diagonals of a parallelogram are not of equal length.
Some special parallelograms are listed in this section like rhombus, square and rectangle.
Properties of all quadrilateral are an important part of this chapter. Students must learn all the properties listed.
A total of 4 exercises are there in this chapter.
In the end, Topic What we have discussed so far is given in that topic all-important key points of the chapter are discussed.
Page No 41:
Question 1:
Given here are some figures.
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
Classify each of them on the basis of the following.
(a) Simple curve
(b) Simple closed curve
(c) Polygon
(d) Convex polygon
(e) Concave polygon
ANSWER:
(a) 1, 2, 5, 6, 7
(b) 1, 2, 5, 6, 7
(c) 1, 2
(d) 2
(e) 1
- We have learnt the angle sum property of a triangle in the earlier class. In Chapter 16 of Class 8, we shall learn concepts based on the angle sum property of a quadrilateral and other polygons. These concepts are explained in detail and exercise-wise solutions are prepared by our expert faculty team in the best possible ways students can understand. Students are advised to refer to RD Sharma Class 8 as reference material, which helps in boosting