Half Yearly Examination-2025
Class: Seven Sub: Mathematics
Chapter: 9.1
1. In the figure, ABC is a triangle in which ABC = 900, BAC = 480 and BD is perpendicular to
AC, Find the remaining angles.
Solution:
Let other angles ABD = x, DBC = y and BCD = z
Since BD AC
ADB = CDB = 900
Now
x + ADB + 480- = 1800
or, x + 900 + 480 = 1800
or, x + 1380 = 1800
or, x = 1800 - 1380
x = 420
Again ABC = 900
y = 900 x = 900 – 420 = 480
and z + 480 + 900 =1800
or, z + 1380 = 1800
z = 1800 – 1380 = 420
x = 420, y = 480 and z = 420
2. The vertical angle of an isosceles triangle is 500. Find the other two angles.
Solution:
Let ABC be isosceles where BAC = 500.
We are to find out the values of other two angles.
Finding the value:
ABC be isosceles
AB = AC
or, ACB = ABC
Now In ABC we have
Class: Seven Sub: Mathematics
Chapter: 9.1
1. In the figure, ABC is a triangle in which ABC = 900, BAC = 480 and BD is perpendicular to
AC, Find the remaining angles.
Solution:
Let other angles ABD = x, DBC = y and BCD = z
Since BD AC
ADB = CDB = 900
Now
x + ADB + 480- = 1800
or, x + 900 + 480 = 1800
or, x + 1380 = 1800
or, x = 1800 - 1380
x = 420
Again ABC = 900
y = 900 x = 900 – 420 = 480
and z + 480 + 900 =1800
or, z + 1380 = 1800
z = 1800 – 1380 = 420
x = 420, y = 480 and z = 420
2. The vertical angle of an isosceles triangle is 500. Find the other two angles.
Solution:
Let ABC be isosceles where BAC = 500.
We are to find out the values of other two angles.
Finding the value:
ABC be isosceles
AB = AC
or, ACB = ABC
Now In ABC we have
