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.
THE ISOSCELES RIGHT TRIANGLE . A N ISOSCELES RIGHT TRIANGLE is one of two special triangles. (The other is the 30Â°-60Â°-90Â° triangle.) The student should know the ratios of the sides. (An isosceles triangle has two equal sides. See Definition 8 in Some Theorems of Plane Geometry. The theorems cited below will be found there.) Theorem. In an isosceles right triangle the sides are in the ratio 1:1:. Proof. In an isosceles right triangle, the equal sides make the right angle. They have the ratio of equality, 1 : 1. To find the ratio number of the hypotenuse h, we have, according to the Pythagorean theorem, h2 = 12 + 12 = 2.