 An angle formed outside of the circle by the intersection of two secants, two tangents or a tangent and a secant is called an exterior angle of the circle. |
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 A line that is tangent to two circles is called a common tangent of the circles. Common tangent is called external tangent if ... |
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 Given a triangle, extend two sides in the direction opposite their common vertex. The circle tangent to these two lines and to the other side of ... |
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 In a triangle, the longer side is opposite the greater angle. In a triangle, the sum of the lengths of two sides is always greater than ... |
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An altitude of a triangle is a line segment that joins the vertex of the triangle with the opposite side and perpendicular to the side.
An isosceles triangle is a triangle with (at least) two equal sides. The two equal sides are called the legs and the unequal side ...
The sum of the angles of a triangle is 180 degrees. The sum of the exterior angles of a triangle is equal to 360 degrees.
A right trapezoid is a trapezoid having two right angles. An isosceles trapezoid is a trapezoid with both legs the same length. ...
Solids