Question

An exterior angle of a triangle is 80° and the interior opposite angles are in the ratio 1 : 3, measure of interior opposite angles are

10⁰, 50⁰
30⁰, 50⁰
20⁰, 60⁰
40⁰, 40⁰​

Answer 1

the angles are 2o nd 60, its option c

Answer 2

We know that,

An exterior angle of a triangle is equal to the sum of the two opposite interior angles.

Here, exterior angle = 80°

ratio of opposite interior angles are 1:3

Let,

Common ratio is = x

So angles are x and 3x

According to the question,

$x + 3x = 80 \\ = > 4x = 80 \\ = > x = \frac{80}{4} \\ = > x = 20$

So 1st angle = x = 20°

2nd angle =3x=3×20 =60°