Use the triangle angle sum theorem to find the third angle of a triangle if the other two angles measure 25 and 68. A: 86 B: 88 C: 77 D: 87

1 answer

The triangle angle sum theorem states that the sum of the interior angles of a triangle is always 180 degrees.

Given the two angles:

  • Angle 1 = 25 degrees
  • Angle 2 = 68 degrees

To find the third angle, we can set up the equation:

\[ \text{Third angle} = 180 - (\text{Angle 1} + \text{Angle 2}) \]

Substituting the values:

\[ \text{Third angle} = 180 - (25 + 68) \]

Calculating the sum of the angles first:

\[ 25 + 68 = 93 \]

Now, substituting back into the equation:

\[ \text{Third angle} = 180 - 93 = 87 \]

So, the third angle measures 87 degrees.

Thus, the correct answer is D: 87.