if acos^2C/2+ccos^2A/2=3b/2 then show that a,b,c are in a.p.
Haimanti , 5 Years ago
Grade 11
Trigonometry> if acos^2C/2+ccos^2A/2=3b/2 then show tha...
1 Answers
Arun
Last Activity: 5 Years ago
we know cosC=2cos^2(C/2)-1
so, a(1+cosC)/2+c(1+cosA)/2=3b/2
a+acosC+c+ccosA=3b
a+c+(acosC+ccosA)=3b
Using By projection formula: (acosC+ccosA)=b
a+c+b=3b
a+c=2b
This shows that a,b,c are in A.P.
Regards
Arun
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