Presentation on theme: "Grade 7 The Shape of Design"— Presentation transcript:
1Grade 7 The Shape of Design AnglesGrade 7The Shape of Design
2Recap Geometrical Terms An exact location on a plane is called a point.PointA straight path on a plane, extending in both directions with no endpoints, is called a line.LineA part of a line that has two endpoints and thus has a definite length is called a line segment.Line segmentA line segment extended indefinitely in one direction is called a ray.Ray
3If we look around us, we will see angles everywhere. Angles In Daily LifeIf we look around us, we will see angles everywhere.
4Ray BA and BC are two non-collinear rays What Is An Angle ?When two non-collinear rays join with a common endpoint (origin) an angle is formed.ARay BABCommon endpointBCRay BCCommon endpoint is called the vertex of the angle. B is the vertex of ÐABC.Ray BA and BC are two non-collinear raysRay BA and ray BC are called the arms of ABC.
5Fact: We can also think of an angle formed by rotating one ray away from its initial position.
6Naming An Angle A B C For example: ÐABC or ÐCBA To name an angle, we name any point on one ray, then the vertex, and then any point on the other ray.ABCFor example: ÐABC or ÐCBAWe may also name this angle only by the single letter of the vertex, for example ÐB.
7Interior And Exterior Of An Angle An angle divides the points on the plane into three regions:Points lying on the angle (An angle)ABCPTXFRPoints within the angle (Its interior portion. )Points outside the angle (Its exterior portion. )
8Measurement Of An Angle Protractor is used to measure and draw angles. Angles are accurately measured in degrees.
9There are four main types of angles. Right angleAcute angleObtuse angleABCABCABCStraight angleBAC
10Right angle: An angle whose measure is 90 degrees. Straight AngleRight AngleAcute AngleObtuse Angle
18Greater than a right angle Which of the angles below is a right angle, less than a right angle and greater than a right angle?1.DEF2.PQRTest Yourself 1Greater than a right angleABCRight angle3.Less than a right angle
19Congruent Angles A B C D E F D E F Two angles that have the same measure are called congruent angles.ABC300DEF300DEF300Congruent angles have the same size and shape.
20Pairs Of Angles : Types Adjacent angles Complimentary angles Supplementary anglesLinear pairs of angles
21Adjacent Angles ABC and DEF are not adjacent angles Two angles that have a common vertex and a common ray are called adjacent angles.CDBACommon rayCommon vertexDEFABCAdjacent Angles ABD and DBCABC and DEF are not adjacent anglesAdjacent angles do not overlap each other.
22ÐABC and ÐDEF are complimentary because Complimentary AnglesIf the sum of two angles is 900, then they are called complimentary angles.600ABC300DEFÐABC and ÐDEF are complimentary becauseÐABC + ÐDEF= 900
23ÐDEF and ÐPQR are not complimentary because Contd….If the sum of two angles is more than 900 or less than 900, then they not complimentary angles.700DEF300pQRÐDEF and ÐPQR are not complimentary becauseÐDEF + ÐPQR= 1000
24ÐPQR and ÐABC are supplementary, because Supplementary AnglesIf the sum of two angles is 1800 then they are called supplementary angles.RQPABC1000800ÐPQR and ÐABC are supplementary, becauseÐPQR + ÐABC= 1800
25ÐDEF and ÐPQR are not supplementary because Contd….If the sum of two angles is more than or less than 1800, then they are not supplementary angles.CBA1100DEF800ÐDEF and ÐPQR are not supplementary becauseÐABC + ÐDEF= 1900
26Two adjacent supplementary angles are called linear pair of angles. 1200600CDPÐAPC + ÐAPD= 1800
27ÐABD and ÐDBC Test Yourself 2 ÐABE and ÐDBA ÐEBA, ÐABC ÐEBD, ÐDBC Name the adjacent angles and linear pair of angles in the given figure:Adjacent angles:CDBAE600300900CDBAE600300900ÐABD and ÐDBCÐABE and ÐDBATest Yourself 2Linear pair of angles:ÐEBA, ÐABCÐEBD, ÐDBC