The problem states that two angles of a triangle are $60^\circ$ and $72^\circ$. We need to find the angles formed by the altitudes of the triangle originating from the vertices of the given angles.
2025/3/27
1. Problem Description
The problem states that two angles of a triangle are and . We need to find the angles formed by the altitudes of the triangle originating from the vertices of the given angles.
2. Solution Steps
Let the angles of the triangle be , , and . We are given and .
The sum of the angles in a triangle is . Therefore,
Let , , and be the altitudes originating from vertices , , and respectively.
Let the angles formed by the altitudes and be and . The point of intersection of the altitudes is the orthocenter.
The altitude from vertex is perpendicular to side , and the altitude from vertex is perpendicular to side . Therefore, the angle between and is supplementary to angle .
The other angle formed by and is
Since the altitudes from and are perpendicular to the sides opposite to and respectively, they form right angles.
Let the altitudes and intersect at . Consider the quadrilateral formed by vertices , , and the foot of the altitude from to , say and the foot of the altitude from to , say . The quadrilateral is . The sum of angles in a quadrilateral is . Thus, . We have and . So , which implies . Thus . The angle formed is , so the other angle is .
The angles formed by and are supplementary to angle .
The other angle is .
The angles formed by and are supplementary to angle .
The other angle is .
3. Final Answer
The angles formed by the altitudes originating from the vertices of the given angles are and . The other possible angles between the altitudes from vertices A and C are and . The other possible angles between the altitudes from vertices B and C are and . The problem asks for the angles formed by the altitudes originating from the vertices of the angles and , which is the angle at the orthocenter, . The supplementary angle to is , thus the angle is . Also, it can be