A Tale of Three Intersecting Lines Class 7 Short Question Answer

A Tale of Three Intersecting Lines Class 7 Short Question Answer

A Tale of Three Intersecting Lines Class 7 Short Question Answer

Question 1.

In the given figure, if y is five times x, find the value of z.

Solution:

y = 5x. So, x + 5x + 60° = 180°

or 6x = 120°

or x = [latex]\frac{120^{\circ}}{6}[/latex] = 20°

So, y = 5 × 20° = 100°

Here, z = 60° + 100° = 160°.

Question 2.

The lengths of two sides of an isosceles triangle are 9 cm and 20 cm. Find the perimeter of the triangle.

Solution:

Since the triangle is isosceles, so, the third side can be 9 cm and 20 cm.

If third side is 9 cm, then 9 cm + 9 cm = 18 cm, which is less than 20 cm. So, 9 cm is not possible.

Thus, third side is 20 cm.

So, perimeter of the triangle is (9 + 20 + 20) cm = 49 cm.

Question 3.

If an exterior angle of a triangle is 110° and one of its interior opposite angles is 40°, find the other two angles of the triangle.

Solution:

The other interior opposite angle of the triangle = 110° - 40° = 70°.

So, third angle = 180° - 40° - 70° = 70°.

Question 4.

In the given figure, find the values of x and y.

Solution:

∠ADB = 180° - 90° = 90°

So, from ∆ADB, x + 55° + 90° = 180°

or x = 180° - 90° - 55° = 35°

From ∆ADC, y + 40° + 90° = 180°

ory = 180° - 40° - 90° = 50°

Question 5.

Two sides of a triangle are 10 cm and 4 cm. Give 5 possible lengths for the third side so that a triangle can be constructed from the three side lengths.

Solution:

Answer is not unique.

5 possible lengths may be 7 cm, 6.5 cm, 7.5 cm, 8 cm and 9 cm, because in each case sum of the two sides will be greater than the third side.