Question 818390:  Explain how to find the orthocenter of a triangle. 
 Answer by richwmiller(17219)      (Show Source): 
You can  put this solution on YOUR website! It where the the three altitudes meet.  
so you need to find the altitudes of at least two of them 
The intersection H of the three altitudes AH_A, BH_B, and CH_C of a triangle is called the orthocenter. The name was invented by Besant and Ferrers in 1865 while walking on a road leading out of Cambridge, England in the direction of London. The trilinear coordinates of the orthocenter are 
cosBcosC:cosCcosA:cosAcosB. 
If the triangle is not a right triangle, then (-1) can be divided through by cosAcosBcosC to give 
secA:secB:secC. 
The orthocenter is Kimberling center X_4. 
The following table summarizes the orthocenters for named triangles that are Kimberling centers. 
 
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