Page 193 - ICSE Math 6

(i) If in DABC AB = BC = CA, then DABC is _________ triangle.

(j) If the sides of a triangle are in the ratio 1 : 2 : 3, then the triangle is _________ triangle.
(k) The three medians of a triangle meet at a point known as the _________.

PRACTICE TIME

1. Define a trapezium, parallelogram and a rectangle.
2. What is a polygon? Name any three polygons having four sides.
3. Find the number of triangles and squares in the given figures.

(a) (b)

4. Classify the triangles with the following side lengths as equilateral, isosceles or scalene.

(a) 4 cm, 4 cm, 5 cm (b) 3 cm, 4 cm, 5 cm (c) 7 m, 7 m, 7 m
5. Classify the triangles with the following angles as acute-angled, obtuse-angled or right- angled.

(a) 40°, 70°, 70° (b) 30°, 140°, 10° (c) 70°, 90°, 20°
6. A mason can arrange 10 identical square tiles along the length of a square floor. How many more
such tiles should he order to completely cover the floor, if he already has 12 tiles?
7. A carpenter has four wooden boards, A, B, C and D, as shown.

A B C D
Which two boards can he directly combine along any one of the sides to make a rectangular door?

THINK SMART

1. Into which triangles a rectangle is divided by one of its diagonals?
2. Explain why the following statements are true or false.
(a) An equilateral triangle is an acute-angled triangle.

(b) All isosceles triangles are obtuse-angled triangle.
(c) A right-angled triangle can be an isosceles triangle.
(d) A right-angled triangle can be a scalene triangle.

(e) A scalene triangle is always an obtuse-angled triangle.
3. Which triangle(s) can have equal median and altitude?

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