Square is also a parallelogram as its opposite sides are parallel.

Squares, rectangles, parallelograms are all quadrilaterals as they all have four sides.

A square can be thought of as a special rhombus because like a rhombus it has all sides equal but all its angles are also equal.

**2.(b)** Give reasons for the following :

(b) A rectangle can be thought of as a special parallelogram.

A rectangle can be thought of as a special parallelogram as it s a parallelogram only but with all angles equal to ninety degrees.

A square can be thought of as a special rectangle as it is a rectangle only but with all sides equal.

(a) True.
(b) True.
(c) True.
(d) True.
(e) False.
(f) False.

(a)(i) Acute angled triangle.
(ii) Isosceles triangle.
(b)(i) Right angled triangle.
(ii) Scalane triangle.
(c)(i) Obtuse angled triangle.
(ii) Isosceles triangle.
(d)(i) Right angled triangle.
(ii) Isosceles triangle.
(e)(i) Acute angled triangle.
(ii) Equilateral triangle.
(f)(i) Obtuse angled triangle.
(ii) Scalane triangle.

**2.** Match the following :

Measure of triangles | Types of triangle |

(i) 3 sides of equal length | (a) Scalene |

(ii) 2 sides of equal length | (b) Isoscles right angled |

(iii) All sides of different length | (c) Obtuse angled |

(iv) 3 acute angles | (d) Right angled |

(v) 1 right angle | (e) Equilateral |

(vi) 1 obtuse angle | (f) Acute angled |

(vii) 1 right angle with two sides of equal length | (g) Isosceles |

Measure of triangles
Types of triangle
(i) 3 sides of equal length
(e)Equilateral
(ii) 2 sides of equal length
(g) Isoscles
(iii) All sides of different length
(a) Scalene
(iv) 3 acute angles
(f) Acute angled
(v) 1 right angle
(d)Right angled
(vi) 1 obtuse angle
(c) Obtuse angled
(vii) 1 right angle with two sides of equal length
(b) Isoscles right angled

(a) Scalane Triangle.
(b) Scalane Triangle.
(c) Equilateral Triangle.
(d) Right angled Triangle.
(e) Right angled isosceles Triangle.
(f) Acute angled Triangle.

(a) CE = 5 - 3 = 2 units
EG = 7 - 5 = 2 units
Therefore CE = EG.
(b) CE = EG therefore PE bisects CG.
(c) PE is the perpendicular bisector for line segments DF and BH
(d) (i) AC = 3 - 1 = 2 units
FG = 7 - 6 = 1 unit
Therefore AC > FG
True
(ii) CD = 4 - 3 = 1 unit
GH = 8 - 7 = 1 unit
Therefore CD = GH
True
...

The angles of the two set quares are
(i) 90o, 60o and 30o
(ii) 90o, 45o and 45o
Yes they have the common angle measure 90o

PQ and XY intersect at A
Therefore

(a) The adjacent edges of a table top are models for perpendicular lines.
(b) The lines of a railway track are not models for perpendicular lines as they are parallel to each other.
(c) The line segments forming the letter ‘L’ are models for perpendicular lines.
(d) The line segments forming the letter ‘V’ are models for perpendicular lines.

ANGLE
MEASURE
TYPE
40o
Acute Angle
125o
Obtuse Angle
85o
Acute Angle
95o
Obtuse Angle
1400
Obtuse Angle
1800
Straight Angle

The angle measure between the hands of the clock in each figure is
(a) 90o
(b) 30o
(c) 180o

(a) Measure of the given along = 40o
(b) Measure of the given along = 130o
(c) Measure of the given along = 65o
(d) Measure of the given along = 135o

(a) An angle whose measure is less than that of a right angle is acute.
(b) An angle whose measure is greater than that of a right angle is obtuse.
(c) An angle whose measure is the sum of the measures of two right angles is straight.
(d) When the sum of the measures of two angles is that of a right angle, then each one of them is acute.
(e) When the sum of the measures of two angles is that of...

By estimation followed by confirmation by measurement we know that the second angle is greater.

Measure of Angle A = 40o
Measure of Angle B = 60o

(a) 45o
(b) 125o
(c) 90o
(d) 60o, 90o and 125o

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