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in a triangle the cosines of two angles are inversely proportional to the sides opposite to the corresponding angled then the triangle is?
1)isoceles
2)right-angled
3)equilateral
4)none of these.
please give the reason for the answer too.

Nishtha Gahlot , 8 Years ago
Grade 12
anser 2 Answers
Saurabh Koranglekar

Last Activity: 5 Years ago

576-1878_1.PNG

Vikas TU

Last Activity: 5 Years ago

Dear student 
acosA=bcosB⇒2RsinAcosA=2RsinBcosB
⇒sin2A=sin2B
A=B
or 2A+2B=180 
A+B=90 
C=90 
So the triangle is right angled triangle and it may be an isosceles triangle as well (90-45-45)
Good Luck 

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