Explanation
Area of a triangle ABC = 12|[x1(y2−y3)+x2(y3−y1)+x3(y1−y2)]|
Substituting the given coordinates, we have
=12[5(7+4))−(4+2)+7(2−7))]
=12(5(11)+4×(−6)+7×(−5))
=12[(55)−(24)−(35)]
=12×|−4|=2 square units.
Consider give the vertex of a triangle are (−2,0),(2,3) and (1,−3).
Let, a triangle ABC, which have vertex A(−2,0),B(2,3) and C(1,−3).
Now, sides of triangle AB,BC and CA are,
AB=√(2+2)2+(3−0)2=5unit
BC=√(1−2)2+(−3−3)2=√37unit
And CA=√(1+2)2+(−3−0)2=3√2unit
Hence, AB≠BC≠CA
So, required triangle is scalene triangle.
Toidentify−whetherABCDisa(i)parallelogram,(ii)rectangle,(iii)square,(iv)scaleneone.Solution−(i)Weknowthatinaparallelogrmthediagonalsbisecteachotheri.ethemidpointsofAC&BDaresame.LetthemidpointofACbeP(x,y).Applyingmidpointtheorem,P(x,y)=(x1+x32,y1+y32)=(−2+42,−1+32)=(1,1).AgainletthemidpointofBDbeQ(p,q).Applyingmidpointtheorem,Q(p,q)=(x2+x42,y2+y42)=(1+12,0+12)=(1,1).∴P(x,y)=Q(p,q)⟹themidpointsofAC&BDaresame.SoABCDisaparallelogram.(ii)IfthediagonalsoftheparallelogramABCDareequalthenitisarectangle.i.eAC=BD.Applyingdistanceformula,AC=√(x1−x3)2+(y1−y3)2=√(−2−4)2+(−1−3)2units=2√13units.BD=√(x2−x4)2+(y2−y4)2=√(1−1)2+(0−2)2units=2units.∴AC≠BD.SoABCDisnotarectagle.Consequently,itisnotasquare.Ans−OptionA.
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