Exercise 8.3.4
1. State whether True or False
2. Identify all the quadrilaterals that have.
(a) four sides of equal length:
(b) four right angles:
3. Explain how a square is.
(i) a quadrilateral: because it has
(ii) a parallelogram: because its opposite sides are
(iii) a rhombus: because all four sides are of
(iv) a rectangle: because it has
4. Name the quadrilaterals whose diagonals.
(i) Diagonals bisect each other:
Parallelogram,
(ii) Diagonals are perpendicular bisectors of each other:
(iii) Diagonals are equal:
Rectangle,
5. Explain why a rectangle is a convex quadrilateral.
In Convex Quadrilaterals Diagonals lie in the interior.
Rectangle ABCD has
Hence,ABCD is a convex Quadrilateral.
6. ABC is a right-angled triangle and O is the mid point of the side opposite to the right angle. Explain why O is equidistant from A,B and C. (The dotted lines are drawn additionally to help you).
Try These
1.What is the sum of the measures of its exterior angles x, y, z, p, q, r?
x,y,z,p,q,r are all exterior angles.
Hence,x+y+z+p+q+r=
2. Is x = y = z = p = q = r? Why?
It is a hexagon with all sides
a + r = a + x = a + y = a + z = a + p = a + q =
Hence,x=y=z=p=q=r
3. What is the measure of each?
(i) exterior angle
All Interior angles are also equal.
Sum of all angles of hexagon is 720.
6a =720, a = 120.
Each exterior angle =r=x=y=z=p=q=180-a =
(ii) interior angle TO DO
4. Repeat this activity for the cases of (i) a regular octagon
Let interior angle be A.
8 * A = 1080
A=
All exterior angles be B.
B=180-135=
(ii) a regular 20-gon
Let interior angle be A
20 * A = 3240
A =
All exterior angles be B.
B=180-162=
Try These
1.Take two identical set squares with angles 30° – 60° – 90° and place them adjacently to form a parallelogram as shown in Fig. Does this help you to verify the above property?
Property : The opposite sides of a parallelogram are of
As we can see in the figure above, the opposite sides of figure are equal.
The figure above is a rectangle which is part of parallelogram.