## Elementary Geometry for College Students (6th Edition)

(a) It is possible for a triangle to be an acute isosceles triangle. One angle has a measure of $x$ where $0 \lt x \lt 90^{\circ}$ The two other angles measure $\frac{180^{\circ}-x}{2}$ (b) It is possible for a triangle to be an obtuse isosceles triangle. One angle has a measure of $x$ where $90^{\circ} \lt x \lt 180^{\circ}$ The two other angles measure $\frac{180^{\circ}-x}{2}$ (c) It is not possible for a triangle to be an equiangular isosceles triangle. If all three angles measure $60^{\circ}$, then the triangle is an equilateral triangle, not an isosceles triangle.