Given triangle $ABC$, the exterior angle at vertex $A$ is $134^\circ$ and the interior angle at vertex $B$ is $62^\circ$. We need to find the third interior angle of the triangle and the angle at which the angle bisectors of angles $A$ and $B$ intersect.

GeometryTrianglesAnglesAngle BisectorsInterior AnglesExterior Angles
2025/3/29

1. Problem Description

Given triangle ABCABC, the exterior angle at vertex AA is 134134^\circ and the interior angle at vertex BB is 6262^\circ. We need to find the third interior angle of the triangle and the angle at which the angle bisectors of angles AA and BB intersect.

2. Solution Steps

First, we find the interior angle at vertex AA. Let this be α\alpha. Since the exterior angle at AA is 134134^\circ, we have
180α=134180^\circ - \alpha = 134^\circ
α=180134=46\alpha = 180^\circ - 134^\circ = 46^\circ
So, the interior angle at vertex AA is 4646^\circ.
Next, we find the interior angle at vertex CC. Let this be γ\gamma. The sum of the interior angles of a triangle is 180180^\circ, so we have
α+β+γ=180\alpha + \beta + \gamma = 180^\circ
46+62+γ=18046^\circ + 62^\circ + \gamma = 180^\circ
108+γ=180108^\circ + \gamma = 180^\circ
γ=180108=72\gamma = 180^\circ - 108^\circ = 72^\circ
So, the interior angle at vertex CC is 7272^\circ.
Now, we find the angle at which the angle bisectors of angles AA and BB intersect. Let II be the point where the angle bisectors of angles AA and BB intersect. Let IAB\angle IAB be α/2\alpha/2 and IBA\angle IBA be β/2\beta/2. The angle bisector of A\angle A is 462=23\frac{46^\circ}{2} = 23^\circ and the angle bisector of B\angle B is 622=31\frac{62^\circ}{2} = 31^\circ.
In triangle AIBAIB, we have
IAB+IBA+AIB=180\angle IAB + \angle IBA + \angle AIB = 180^\circ
23+31+AIB=18023^\circ + 31^\circ + \angle AIB = 180^\circ
54+AIB=18054^\circ + \angle AIB = 180^\circ
AIB=18054=126\angle AIB = 180^\circ - 54^\circ = 126^\circ
So, the angle at which the angle bisectors of angles AA and BB intersect is 126126^\circ.

3. Final Answer

The third angle of the triangle is 7272^\circ and the angle at which the angle bisectors of angles AA and BB intersect is 126126^\circ.

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