How many degrees are in a triangle if two angles are 35° and 65°?

How many degrees are in a triangle if two angles are 35° and 65°?

• A. 70°
• B. 75°
• C. 80°
• D. 85°

Answer: (B)

To find the measure of the third angle in a triangle when two angles are already known, you can use the fundamental property of triangles, which states that the sum of the interior angles of a triangle is always 180 degrees. In this case, you have the two angles measuring 35 degrees and 65 degrees. To find the third angle, you can start by adding the two known angles together: 35° + 65° = 100°. Then, subtract this sum from 180° to find the measure of the third angle: 180° - 100° = 80°. Thus, the measure of the third angle is 80 degrees, which aligns with one of the given choices. The total of all three angles in the triangle now confirms that they add up to 180 degrees, validating the calculation.

To find the measure of the third angle in a triangle when two angles are already known, you can use the fundamental property of triangles, which states that the sum of the interior angles of a triangle is always 180 degrees.

In this case, you have the two angles measuring 35 degrees and 65 degrees. To find the third angle, you can start by adding the two known angles together:

35° + 65° = 100°.

Then, subtract this sum from 180° to find the measure of the third angle:

180° - 100° = 80°.

Thus, the measure of the third angle is 80 degrees, which aligns with one of the given choices. The total of all three angles in the triangle now confirms that they add up to 180 degrees, validating the calculation.