ISLAMIYA ENGLISH SCHOOL, ABU DHABI.



GRADE: 7CIRCLES CHAPTER: 11DEFINITIONS:The circle is a two dimensional plane shape. Circle is simply the set of all points’ equidistance from a center point.The distance r from the center of the circle to the circumference is called the radius. Twice the radius 2r is called the diameter.Diameter = 2 × radius.The circumference is the distance once around the circle.circumferencediameter=π .π=3.14 or 227.KEY PPOINTS:A line that goes from one point to another on the circle’s circumference is called a chord.A part of the circumference is called an arc.The pizza slice is called a sector.The slice made by a chord is called a segment.Quarter of a circle is called a quadrant.Half a circle is called a semi-circle.FORMULAE:Circumference C=πd.Circumference C=2πr.Radius r=C2πArea A=πr2.Length of arc l=θ3602πr.Perimeter of sector P=l of arc+2r.Area of sector A=θ360πr2.NOTE:-Use π=3.14 or 227 for the given questions in this chapter.PART-AThe radius of a circle is 2 inches. What is the diameter?The diameter of a circle is 3 cm .What is the circumference?The radius of a circular ring is 4 feet. What is the circumference of the ring?Find the circumference of a circle whose diameter is 2.8 m.Find the circumference of a circle of radius 35 mm.The circumference of a circle is 15.7 cm. What is the diameter? Take π=3.14.The circumference of a compact disc is 28.26 cm .What is the radius?Find the area of a circle with radius 12 mm.Find the area of a circle of diameter 16 m.An inner plate has a radius of 6 cm. What is the area of the plate?PART-BFind the perimeter of the given shape.20mFind the perimeter of the given shape. Use π=227.14m14mFind the area of the sector.30°28cmFind the perimeter and area of a quarter of a circle whose is radius is 7m.Find the area of the given shape.3m8mPART – C (Bravo!)The diameter of a bicycle wheel is 25 inches. How far does the wheel move in one turn?A circular table has diameter 1.4 m .What is the area of the top of the table?The diagram shows two circles with centre O. The radius of the outer circle is 3 units and the radius of inner circle is 2 units .What is the area of the shaded ring?(annulus)A semi-circular carpet has a diameter of 7ft. What is the area of the carpet?The below diagram shows a logo design consisting of two circles joined together. The top circle has radius 3 units and center O.The bottom circle has radius 5 units and center P. What is the area of the logo?53mx-----------------x----------------x ................
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