Math Problem Statement

In △ABC, bisectors of ∠A and ∠B intersect at point O. If ∠C = 70°, find the measure of ∠AOB.

Solution

The problem is asking to find the measure of angle AOB\angle AOB, where OO is the point of intersection of the angle bisectors of angles AA and BB in triangle ABC\triangle ABC. We are given that C=70\angle C = 70^\circ.

Solution:

In a triangle, the sum of the interior angles is always 180180^\circ. So we can find the sum of A\angle A and B\angle B as follows:

A+B+C=180\angle A + \angle B + \angle C = 180^\circ

Since C=70\angle C = 70^\circ, we have:

A+B+70=180\angle A + \angle B + 70^\circ = 180^\circ

A+B=110\angle A + \angle B = 110^\circ

Next, because the bisectors of A\angle A and B\angle B intersect at point OO, the angle AOB\angle AOB at the incenter (point OO) is given by the formula:

AOB=90+C2\angle AOB = 90^\circ + \frac{\angle C}{2}

Substitute C=70\angle C = 70^\circ:

AOB=90+702\angle AOB = 90^\circ + \frac{70^\circ}{2}

AOB=90+35=125\angle AOB = 90^\circ + 35^\circ = 125^\circ

Final Answer:

The measure of AOB\angle AOB is 125125^\circ.


Would you like further clarification on this solution, or any additional steps explained in detail?

Here are 5 related questions to consider:

  1. How do you derive the sum of interior angles of a triangle?
  2. What is the importance of the incenter in triangle geometry?
  3. Why do we use the formula AOB=90+C2\angle AOB = 90^\circ + \frac{\angle C}{2} for this scenario?
  4. Can this method be generalized to other types of triangles?
  5. How would the solution change if C\angle C were different?

Tip: Remember that the incenter of a triangle is equidistant from all sides of the triangle, and is the center of the inscribed circle.

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Math Problem Analysis

Mathematical Concepts

Triangle Geometry
Angle Bisectors
Incenter

Formulas

Sum of interior angles of a triangle = 180°
∠AOB = 90° + ∠C/2

Theorems

Incenter Theorem
Sum of Angles in a Triangle

Suitable Grade Level

Grades 9-11