1. (1) Parallel lines: Two lines, having no common points, are parallel lines. [Undefined term: The distance between the two lines are constant] (i) Perpendicular lines: Two lines which form angle of 90° with each other, are perpendicular lines. (iii) Line segment: The line which have two end point, isRead more

    (1) Parallel lines: Two lines, having no common points, are parallel lines. [Undefined term: The distance between the two lines are constant]
    (i) Perpendicular lines: Two lines which form angle of 90° with each other, are perpendicular lines.
    (iii) Line segment: The line which have two end point, is a line segment.
    (iv) Radius of a Circle: The line segment from the centre of circle to the circle is radius of circle.
    (v) Square: A quadrilateral having all sides equal and all angles right angle.

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  2. There are several undefined terms which should be listed. They are consistent, because they deal with two different situations (i) says that Given two points A and B, there is a point C lying on the line in between them; (ii) says that: Given A and B, you can take C not lying on the line through A aRead more

    There are several undefined terms which should be listed. They are consistent, because they deal with two different situations
    (i) says that
    Given two points A and B, there is a point C lying on the line in between them;
    (ii) says that:
    Given A and B, you can take C not lying on the line through A and B.
    These ‘postulates’ do not follow from Euclid’s postulates. However, they follow from Axiom 5.1.

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  3. Given: AC = BC ⇒ AC + AC = AC + BC [∵ Equals are added to equals] ⇒ 2AC = AB [∵ AC +BC coincides with AB] ⇒ AC = 1/2 AB [∵ Things which are halves of the same things are equal to one another]

    Given: AC = BC
    ⇒ AC + AC = AC + BC [∵ Equals are added to equals]
    ⇒ 2AC = AB [∵ AC +BC coincides with AB]
    ⇒ AC = 1/2 AB [∵ Things which are halves of the same things are equal to one another]

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  4. (i) False, as there are infinite number of line that can pass through one point. (ii) False, because one and only one line can be drawn through two distinct points. (iii) True, because a terminated line can be produced both the sides infinitely. (iv) True, if two circles are equal (i.e. their areasRead more

    (i) False, as there are infinite number of line that can pass through one point.
    (ii) False, because one and only one line can be drawn through two distinct points.
    (iii) True, because a terminated line can be produced both the sides infinitely.
    (iv) True, if two circles are equal (i.e. their areas πr² are equal), then their radii are also equal.
    (v) True, according to Euclid’s axiom, “Things which are equal to the same thing are equal to one another”

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  5. (i) To represent the equation 2x + 9 = 0 in one variable, we will use number line. 2x + 9 = 0 ⇒ x = -9/2 (ii) To represent the equation 2x + 9 = 0 in two variable, we will use Cartesian plane. Now the equation: 2x + 0.y = -9 ⇒ x = (-9 - 0.y)/2 Putting y = 1, we have, x = (-9 - 0 × 1)/2 = -9/2 PuttinRead more

    (i) To represent the equation 2x + 9 = 0 in one variable, we will use number line.
    2x + 9 = 0
    ⇒ x = -9/2
    (ii) To represent the equation 2x + 9 = 0 in two variable, we will use Cartesian plane. Now the equation:
    2x + 0.y = -9
    ⇒ x = (-9 – 0.y)/2
    Putting y = 1, we have, x = (-9 – 0 × 1)/2 = -9/2
    Putting y = 2, we have, x = (-9 – 0 × 2)/2 = -9/2
    Hence, A(-9/2, 1) and B(-9/2, 2) are the two solutions of the given equation.

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