ConstructionModerate1 mark
11(b)
Use ruler and compasses only for the following questions. All constructions lines and arcs must be clearly shown.
Construct a Δ ABC in which BC = 6.5 cm, ∠ ABC = 60°, AB = 5 cm.
Topic: Loci
Previous-year question practice database
Answer
Solution diagram

Exam answer
- Measure XY. XY=5cm
Explanation
(i) Steps of construction:
- Draw BC=6.5cmusing a ruler.
- WithBas thecentreandradiusequal toapproximately half of BC,
draw anarc that cuts thesegment BCat Q.
- WithQ as thecentre,andsameradius,cut thepreviousarcat P.
- JoinBPandextendit.
- WithBas thecentreandradius5cm, draw anarc that cuts the
armPBtoobtain point A.
- Join AC toobtain ΔABC.
(ii)Stepsforconstruction :
- With Aas thecentreandradius3.5cm,draw acircle.
- Thecircumferenceof acircleis therequiredlocus.
(iii)Stepsforconstruction :
- WithCas thecentreand withradiusof a lengthless than CA orBC,
draw anarc tocut the linesegments ACandBCat DandErespectively.
- With thesameradiusorasuitableradiusand withDas thecentre,
draw anarcof acircle.
- With thesameradiusand withEas thecentredraw anarcsuch that
thetwoarcsintersect at H.
- JoinCandH.
- CHis thebisectorof ÐACBandis therequiredlocus.
(iv) Stepsforconstruction:
- Weknown that thepointsat a distanceof 3.5cmfrom A will
surely lieon thecircle withcentre A.
- Also, thepointson theanglebisectorCHare thepoints equidistant from
ACandBC.
- Mark X and Y whichareat theintersectionof thecircleand theangle
bisectorCH.
- Measure XY. XY=5cm
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