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**1.**a polygon with four equal sides and four right angles. Area= a^2**4.**Trigonometric ratio. Formula= p/h**6.**the length of a straight line through the centre of a circle. formula=2r**8.**a quantity obtained by the addition of a group of numbers. Ex 3+7**9.**a point equidistant from the ends of a line or the extremities of a figure. Has a theorem based on it.**10.**a parallelogram with four right angles. Area= lb**11.**An angle less than 90 degrees but more than 0 degrees, all angles of equilateral are of this kind.**12.**a triangle that contains an obtuse interior angle. Ex △ABC in which ∠A= 100degree,∠B= 40degree,∠C=40degree**13.**a continuous portion of a circle of two types minor and major.**14.**a quadrilateral whose opposite sides are parallel and equal. formula of area = bh**17.**the extent of a 2-dimensional surface enclosed within a boundary.Ex 6a^2**18.**being everywhere equidistant and not intersecting. Opposite lines are like this in a parallelogram.**19.**two angles whose sum is a right angle.For example, a 50-degree angle and a 40-degree angle.**20.**A plane figure, area= ∏r^2

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**2.**elevation above sea level or above the earth's surface.All triangles have three of this.**3.**an area that is in the middle of some larger region. It is found in a circle.**5.**The length of the closed curve of a circle. formula= 2∏r**7.**a four-sided polygon. Ex rectangle**15.**All sides of this triangle are equal. Each angle is 60degree**16.**a line enclosing a plane area. Ex 2(l+b)