Page 120 - classs 6 a_Neat
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2. Write the adjacent angles in the following figures. 4. Fill in the blanks.
a. A median of a triangle is the line segment joining a vertex to the
of the opposite side.
b. is the point where the three medians of a triangle meet.
c. An altitude of a triangle is the drawn from a vertex to the opposite side.
d. An angle greater than 0° and less than 90° is called an angle.
e. An angle that measures 90° is called a angle.
f. A straight angle measures
QUADRILATERALS
QUADRILATERAL A simple closed.figure bounded byfour line segments is called a quadrilateral.
In the adjacent figure, ABCD is a quadrilateral.
A quadrilateral ABCD has:
(i) Four vertices, namely, A, B, C and D.
(ii) Four sides, namely, AB, BC, CD and DA.
(iii) Four angles, namely, DAB, ABC, BCD and CDA, to be
denoted by A, B, C and LD respectively.
3. (iv) Two diagonals, namely, AC and BD.
ADJACENT SIDES Two sides of a quadrilateral which have a common end point are called its adjacent sides.
Thus, AB, BC; BC, CD; CD, DA, and DA, AB are four pairs of adjacent sides of the quadrilateral
ABCD.
OPPOSITE SIDES Two sides of a quadrilateral are called its opposite sides if they do not have a common end
point.
Study the triangle given above. Thus, AB, DC, and AD, BC are two pairs of opposite sides of the quadrilateral ABCD.
a. List the three vertices of the triangle.
b. List the three arms or sides of the triangle. ADJACENT ANGLES Two angles of a quadrilateral having a common side are called its adjacent angles.
c. List the three angles of the triangle. Thus, A, B; B, C; C, D; and D, A are four pairs of adjacent angles of the quadrilateral ABCD.
∠
∠
∠
∠
∠
4. Draw separate figures to represent CED, ABC, POQ, MON and XYZ. OPPOSITE ANGLES Two angles of a quadrilateral which are not adjacent angles are known as the opposite
5. PQ and PR are any two rays. Do they always form an angle? Why? angles of the quadrilateral.
6. In the figure given below, name all the eight angles. Thus, A, C, and B, D are two pairs of opposite angles of the quadrilateral ABCD.
REMARK The figure given below is also a figure obtained by joining four line segments
AB, BC, CD and DA But ABCD is not a quadrilateral, since these line segments
intersect at points other than their end points.
