Area Of Plane Dorahab

GOVT. SEN.SEC. SCHOOL, DORAHA Area of Plane Figure The figures which can be drawn in one plane are called plane figures. For example, triangles, quadrilaterals and circles etc. are plane figures.

Polygon A close plane figure formed by n line segments is called an n-sided polygon. Thus, a closed figure of three sides is a triangle, a closed figure of four sides is a quadrilateral and a closed figure of five sides is called a pentagon. A polygon is called a regular polygon if all its sides and angles are equal.

Triangle A Closed figure obtained by joining three non-collinear point is called a triangle. In fig. ABCD a, b, c are sides, h altitude. s= (a+b+c)/2

Area of triangle= ½(ch)

Right Triangle A triangle, one of whose angle is a right angle i.e. of 90o is called a Right Angled Triangle or Simply a Right Triangle. In fig ABC d=√b²+h²

Area of Right Triangle =½(bh)

Isosceles Right Triangle A triangle, one of whose angle is a right angle i.e. of 90o,with two equal sides and two other equal angles always of 45° In Fig. ABC d=a√2

Area of Isosceles Right Triangle= ½a²

Equilateral Triangle A triangle having all three sides of equal length. The angles of an equilateral triangle all measure 60 degrees. In Fig. ABC h= √3/2a

Area of Equilateral Triangle= 1/2ah, √3/4a²

Rectangle A four-sided polygon having all right angles. The sum of the angles of a rectangle is 360 degrees In Fig. ABCD a=length, b=breadth.

Area of Rectangle= a*b

Square A four-sided polygon having equal-length sides meeting at right angles. The sum of the angles of a square is 360 degrees. In Fig. ABCD a= side

Area of Square= a²

Parallelogram A four-sided polygon with two pairs of parallel sides. The sum of the angles of a parallelogram is 360 degrees. In Fig. ABCD a= side, b=side, h=distance between parallel sides of length a.

Area of Parallelogram= a*h

Rhombus A four-sided polygon having all four sides of equal length. The sum of the angles of a rhombus is 360 degrees. In Fig. ABCD a=side, d1d2 -are the diagonals.

Area of Rhombus= ½ (d1*d2)

Trapezium A four-sided polygon having exactly one pair of parallel sides. The two sides that are parallel are called the bases of the trapezium. The sum of the angles of a trapezium is 360 degrees. In Fig. ABCD a, b= parallel sides, h=distance between them.

Area of Trapezium= ½(a+b) h

Circle A circle is the collection of points in a plane that are all the same distance from a fixed point. The fixed point is called the center. A line segment joining the center to any point on the circle is called a radius. In this fig. r-radius

Area of circle= π r2

BIBLIOGRAPHY •

TEXT BOK OF MATHEMETICS (P.S.E.B) OF CLASS 9TH

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TEXT BOK OF MATHEMETICS (P.S.E.B) OF CLASS 7TH

SOFTWARE USED •

MS-PAINT

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MS-WORD