Art of Problem Solving

1974 IMO Problems/Problem 2: Difference between revisions

Elvis (talk | contribs)
Created page with "In the triangle ABC; prove that there is a point D on side AB such that CD is the geometric mean of AD and DB if and only if sin A sin B is less than or equal to sin²(C/2)"
 
Speet (talk | contribs)
No edit summary
Line 1: Line 1:
In the triangle ABC; prove that there is a point D on side AB such that CD
In the triangle ABC; prove that there is a point D on side AB such that CD
is the geometric mean of AD and DB if and only if
is the geometric mean of AD and DB if and only if  
<math>\sin{A}\sin{B} \leq  \sin^2 (\frac{C}{2})</math>.


      sin A sin B is less than or equal to sin²(C/2)
==Solution==
 
Since this is an "if and only if" statement, we will prove it in two parts.
 
Part 1:

Revision as of 16:38, 6 January 2019

In the triangle ABC; prove that there is a point D on side AB such that CD is the geometric mean of AD and DB if and only if $\sin{A}\sin{B} \leq  \sin^2 (\frac{C}{2})$.

Solution

Since this is an "if and only if" statement, we will prove it in two parts.

Part 1: