Wiktionary
n. (context geometry English) A triangle having at least two sides equal.
WordNet
n. a triangle with two equal sides
Wikipedia
In geometry, an isosceles triangle is a triangle that has two sides of equal length. Sometimes it is specified as having two and only two sides of equal length, and sometimes as having at least two sides of equal length, the latter version thus including the equilateral triangle as a special case.
By the isosceles triangle theorem, the two angles opposite the equal sides are themselves equal, while if the third side is different then the third angle is different.
By the Steiner–Lehmus theorem, every triangle with two angle bisectors of equal length is isosceles.
Usage examples of "isosceles triangle".
Let fall the perpendicular KQ, and by similar triangles, and from the fact that HKI is an isosceles triangle by the construction, it can be proved that HI is half of HB.
Of course, what he really wanted to do was to erect an isosceles triangle on a base of eleven miles, having two sides of twenty-one miles each.
I had noticed that whenever I built a fire, Ajor outlined in the air before her with a forefinger an isosceles triangle, and that she did the same in the morning when she first viewed the sun.
Jack's certainties had vanished an hour ago: his neat isosceles triangle had fled down the wind, routed by a thousand fresh unknown quantities.
It was an adult, as was known by its six rows of teeth placed in an isosceles triangle in the upper jaw.
It may have been pear-shaped when it was surveyed a couple of centuries ago, but erosion has changed it to an isosceles triangle.
And it was open and from where we were standing we could see the nose of the dead Mr Penrose rising from it like a pink sharks fin or an isosceles triangle of flesh, or in fact numerous other things of approximately the same shape.
Assuming that her estimate of forty-five degrees, at her first location, was close, and that she was directly over the stone 250 paces on, then the angle between stone, herself, and the first position was ninety degrees, and the original sight line was the hypotenuse of a right isosceles triangle.
America Shaftoe sits, jeaned and barefoot, in the blue light of a window, bobby pins sprouting from chapped lips, looking at her face in an isosceles triangle of mirror whose scalpel-sharp edges depress but do not cut the pink skin of her fingertips.
Standing facing them at the apices of a flat isosceles triangle were the gray-headed man who'd spoken her name, a young girl of eleven in a white shapeless frock, and another man whose face looked sunburned.
Project the line of the first three shells and then the line of these three and you have two sides of an isosceles triangle.