Question

if the second angle is 20% more than the first angle and the third angle is 20% less than the first angle in a triangle, then find the three angles of the triangle

Answer 1

Explanation:

If the second angle's measure is based on the first angle's measure, and the third angle's measure is also based on the first angle's measure, then the first angle is the main angle. We will call that x.

1st angle: x

2nd angle: x + 20%

3rd angle: x - 20%

By the Triangle Angle-Sum Theorem, all those angles will add up to 180, so:

x + (x + 20%) + (x - 20%) = 180 and

3x = 180 so

x = 60. That means that

2nd angle: 60 + (.2*60) which is

60 + 12 = 72 and

3rd angle: 60 - (.2*60) which is

60 - 12 = 48. Let's check those angles. If

∠1 = 60

∠2 = 72

∠3 = 48,

then ∠1 + ∠2 + ∠3 = 180 and

60 + 72 + 48 does in fact equal 180, so you're done!