The acute △ A B C is such that:
Find the smallest integer upper bound of h A m A + h B m B + h C m C .
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@Sathvik Acharya I think you meant h A O D + h B O E + h c O F in the second claim.
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Yes, I have made the necessary corrections. Thank you!
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Your welcome. Just one more question - you have assumed that we are in an acute angled triangle, but the question doesn't state that anywhere. @Sathvik Acharya
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@N. Aadhaar Murty – You are right, the proof holds only for acute triangles, also I am not sure if equality can be achieved.
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Let r , R and S represent the inradius , circumradius and area of the triangle respectively.
Claim: h A 1 + h B 1 + h C 1 = r 1 Proof: h A 1 + h B 1 + h C 1 = 2 S a + 2 S b + 2 S c = 2 S a + b + c = r 1
Let O the center of the circumcircle of △ A B C and D , E , F be the midpoints of side B C , C A , A B respectively.
Claim: h A O D + h B O E + h C O F = 1 Proof: O D ⋅ a + O E ⋅ b + O F ⋅ c = a ⋅ h A = b ⋅ h B = c ⋅ h C = 2 S ⟹ h A O D + h A O E + h C O F = 1
Also, m A = A D ≤ O A + O D ⟹ m A ≤ R + O D . Writing similar inequalities and adding up we get, h A m A + h B m B + h C m C ≤ R ( h A 1 + h B 1 + h C 1 ) + ( h A O D + h A O E + h C O F )
Using the above claims we get the well known inequality, h A m A + h B m B + h C m C ≤ 1 + r R
Therefore the maximum value of h A m A + h B m B + h C m C is 4