The problem involves an isosceles triangle $\triangle JKL$ with equal sides $JK = KL = 7$, and one known angle $\angle J = 25^\circ$. We are tasked with finding the measure of angle $\angle L$.

Solution:

1. In an isosceles triangle, two of the angles opposite the equal sides are congruent. Therefore, $\angle L = \angle J$.

2. Given that $\angle J = 25^\circ$, we conclude that $\angle L = 25^\circ$ as well.

3. To verify, the sum of the angles in a triangle is always $180^\circ$. Thus: $\angle J + \angle K + \angle L = 180^\circ$ Substituting the known values: $25^\circ + \angle K + 25^\circ = 180^\circ$ Simplifying: $50^\circ + \angle K = 180^\circ$ $\angle K = 180^\circ - 50^\circ = 130^\circ$

Thus, $\angle L = 25^\circ$, and the correct answer is C. 25°.

Would you like any further explanation?

5 Related Questions:

1. How do you calculate the angles in an equilateral triangle?
2. What are the properties of isosceles triangles?
3. How do you find the third angle if two angles are given in any triangle?
4. Can an isosceles triangle have angles other than acute angles?
5. What is the exterior angle theorem, and how does it apply to triangles?

Tip:

When working with isosceles triangles, always remember that the angles opposite the equal sides are also equal.