Question

5. If the angles of a triangle are in the ratio 1:2:1, find all the angles of the triangle
b. In an isosceles triangle, a base angle is four times its vertical angle. Find all the
228 ICSE Understanding Mathematics - VII
Calculate the size of each lettered angle in the following figures :
35°
+
Classify the triangle in two different ways.
angles of the triangle​

Answer 1

Answer:

a) let the angles of triangles 1x , 2x , 1x

1x+2x+1x=180

4x=180

x= 180 ÷4

x= 45

so angles of triangle will be

45,90,45

Answer 2

Q1) Ratio of angles= 1:2:1

Let the angles be 1x , 2x , 1x respectively.

Sum of all angles in a triangle = 180°

1x+2x+1x=180

4x=180

x=180/4

x=45

Angles are 1x45 , 2x45 , 1x45

=45° , 90° , 45°.

Q2) An isosceles triangle has two equal base angle and one unequal vertical angle.

Let the vertical angle be X

According to the question, base angles = 4X. (four time the vertical angle)

sum of all angles = 180°

x+4x+4x = 180

9x=180

x=180/9

x=20

Vertical angle = X = 20°

Base angles = 4X = 4x20 = 80°