The Battle of Fredericksburg was fought December 11â15, 1862, in and around Fredericksburg, Virginia, between General Robert E. Lee 's Confederate Army of Northern Virginia and the Union Army of the Potomac, commanded by Major General Ambrose Burnside.
In an isosceles triangle that has exactly two equal sides, the equal sides are called legs and the third side is called the base. The angle included by the legs is called the vertex angle and the angles that have the base as one of their sides are called the base angles.
Use isosceles and equilateral triangles. Using the Base Angles Theorem. A triangle is isosceles when it has at least two congruent. sides. When an isosceles triangle has exactly two congruent. sides, these two sides are the legs. The angle formed by the. legs is the vertex angle. The third side is the base of the. isosceles triangle.