Page 182 - Start Up Mathematics_7

6. Explain how can we find the sum of the angles of a quadrilateral using the angle sum property
of a triangle. Can you generalize the result taking example of a pentagon, hexagon, etc., i.e.,
for any polygon?

Some NCERT Textbook Questions

1. Find the value of the unknown interior angle x in the following figures:

50° 70° 125°
(i) (ii) (iii)
x
x 115° 100° x

60° 80° x
(iv) (v) (vi)
35°
120° 30° x 75°
x

2. Find the values of the unknowns x and y in the following diagrams:

80°

x 50°
(i) (ii) y (iii)

50° y 120° x y 60°
50° x

x
90°
y
(iv) (v) y (vi)
30° x
60° y
x x x x

3. The lengths of two sides of a triangle are 12 cm and 15 cm. Between what two measures
should the length of the third side fall?

4. A 15 m long ladder reached a window 12 m high from the ground on
placing it against a wall at a distance a. Find the distance of the foot of 15 m 12 m
the ladder from the wall.

a
5. A tree is broken at a height of 5 m from the ground and its top touches the ground at a distance
of 12 m from the base of the tree. Find the original height of the tree.

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