What is the orthocenter of a triangle with corners at #(2 ,2 )#, #(5 ,1 )#, and (4 ,6 )#?

1 Answer
Aug 10, 2018

#(4/7,12/7)#

Explanation:

#"We require to find the equations of 2 altitudes and "#
#"solve them simultaneously for orthocentre"#

#"label the vertices"#

#A=(2,2),B=(5,1)" and "C=(4,6)#

#color(blue)"Altitude from vertex C to AB"#

#"calculate slope m using "color(blue)"gradient formula"#

#•color(white)(x)m=(y_2-y_1)/(x_2-x_1)#

#m_(AB)=(1-2)/(5-2)=-1/3#

#m_("altitude")=-1/m=-1/(-1/3)=3#

#"using "m=3" and "(a,b)=(4,6)#

#y-6=3(x-2)larry-b=m(x-a)#

#y-6=3x-6#

#y=3xto(1)#

#color(blue)"Altitude from vertex A to BC"#

#m_(BC)=(6-1)/(4-5)=-5#

#m_("altitude")=-1/(-5)=1/5#

#"using "m=1/5" and "(a,b)=(2,2)#

#y-2=1/5(x-2)#

#y-2=1/5x-2/5larrcolor(blue)"multiply through by 5"#

#5y-10=x-2#

#5y=x+8#

#y=1/5x+8/5to(2)#

#"solving equations "(1)" and "(2)#

#3x=1/5x+8/5rArrx=4/7#

#y=3xx4/7=12/7#

#"orthocentre "=(4/7,12/7)#