Question

Solve by making an equation.

The second angle of a triangle is 20 degrees greater than the first angle. The third angle is twice the second. Find the three angles. (Note: in any triangles, angle measures add up to … how many degrees?)

Answer 1

Let us assume that the F is the first angle, S is the second and T is the third angle.

We know that
- F + S + T = 180°
- S = F + 20°
- T = 2S

We can substitute the S and T values into F, In this case, we will say that:
F + F + 20° + 2 (F + 20°) = 180°
2F + 20° + 2F + 40° = 180°
4F + 60° = 180°
4F = 180° - 60°
F = 120 ÷ 4
∴ F = 30°

S = F + 20°
∴ S = 50°

T = 2S
∴ T = 100°

To make sure that we have worked this out correctly, the angles should add up to give us 180°

Therefore, 30° +50° + 100° = 180°

Hope this helped x