Q. 5
In an isosceles triangle, one angle is 70°. The other two angles are of
(i) 55° and 55°
(ii) 70° and 40°
(iii) any measure
In the given option(s) which of the above statement(s) are true?
A. (i) only
B. (ii) only
C. (iii) only
D. (i) and (ii)
Answer :
Given: An isosceles triangle with one angle is 70°
Formula Used/Theory:-
In an isosceles triangle 2 angles are equal corresponding with 2 equal sides
⇒ If 70° is 3rd angle of triangle
Then;
70° + x + x = 180°
2x = 180° - 70°
x = 
x = 55°
Both angles are 55°
⇒ If 70° is Base angle of isosceles triangle
Then;
70° + 70° + x = 180°
x = 180° - 140°
x = 40°
one angle is 40° and another is 70°
∴ the angles can be either 55°, 55° or 70°, 40°
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