Mathematics - Properties of Triangle Question with Solution | TestHub
MathematicsProperties of Triangler1,r–R formula basedMedium2 minQB
MathematicsMediumsingle choice
In triangle ABC, A-B=120° and R=8r. Find (1+cos C)/(1-cos C).
Options:
Answer:
B
Solution:
r/R=4 sin(A/2)sin(B/2)sin(C/2)=1/8. Using 2sin(A/2)sin(B/2)=cos((A-B)/2)-cos((A+B)/2)=1/2-sin(C/2), put t=sin(C/2)>0. Then (1/8)=2t(1/2-t)=t-, so (4t-1)²=0 and t=1/4. Thus cos C=1-=7/8 and the requested ratio is 15.
Stream:JEESubject:MathematicsTopic:Properties of TriangleSubtopic:r1,r–R formula based
⏱ 2mℹ️ Source: QB
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