FIND ORTHOCENTER OF A TRIANGLE WITH GIVEN VERTICES

Here we are going to see how to find orthocenter of a triangle with given vertices.

What is Orthocenter ?

It can be shown that the altitudes of a triangle are concurrent and the point of concurrence is called the orthocentre of the triangle.The orthocentre is denoted by O.

Let ABC be the triangle AD,BE and CF are three altitudes from A, B and C to BC, CA and AB respectively.

Steps Involved in Finding Orthocenter of a Triangle :

• Find the equations of two line segments forming sides of the triangle.
• Find the slopes of the altitudes for those two sides.
• Use the slopes and the opposite vertices to find the equations of the two altitudes.
• Solve the corresponding x and y values, giving you the coordinates of the orthocenter.

Finding Orthocenter of a Triangle - Examples

Example 1 :

Find the co ordinates of the orthocentre of a triangle whose vertices are (3, 4) (2, -1) and (4, -6).

Solution :

Let the given points be A (3, 4) B (2, -1) and C (4, -6)

Slope of AC  =  [(y₂ - y₁)/(x₂ - x₁)]

A (3, 4) and C (4, -6)

here x₁  =  3, x₂  =  4, y₁  =  4 and y₂  =  -6

  =  [(-6-4)/(4-3)]

  =  (-10)/1

  = -10

Slope of the altitude BE  =  -1/ slope of AC

  =  -1/(-10)

  =  1/10

Equation of the altitude BE :

(y - y₁)  =  m (x -x₁)

Here B (2, -1) and m  =  1/10

 (y - (-1))  =  1/10 (x - 2)

10 (y + 1)  =  (x - 2)

10y + 10  =  x - 2

x - 10y - 2 - 10  =  0  

x - 10y - 12  =  0

x - 10y - 12  =  0

x  =  10y + 12  --------(1)

Slope of BC  =  (y₂ - y₁)(x₂ - x₁)]

B (2,-1) and C (4,-6)

here x₁ = 2,x₂ = 4,y₁ = -1 and y₂ = -6

  =  [(-6 - (-1))/(4 - 2)]

  =  (-6 + 1)/2

   =  -5/2

Slope of the altitude AD  =  -1/ slope of AC

=  -1/(-5/2)

=  2/5

Equation of the altitude AD :

(y - y₁)  =  m (x - x₁)

Here A(3, 4)  m  =  2/5

(y - 4)  =  2/5 (x - 3)

5(y - 4)  =  2(x - 3)

5y - 20  =  2x - 6

2x - 5y - 6 + 20  =  0

2x - 5y + 14  =  0 --------(2)

Substituting (1) into (2), we get

2(10y + 12) - 5y + 14  =  0

20y + 24 - 5y + 14  =  0

15y + 38  =  0

15y  =  -38

y  =  -38/15

By applying y  =  -38/15 in (1), we get

x  =  10(-38/15) + 12

x  =  -76/3  +  12

x  =  -40/3

Therefore the orthocenter is (-40/3, -38/15).

After having gone through the stuff given above, we hope that the students would have understood how to find the orthocenter of a triangle with given vertices.

If you need any other stuff in math, please use our google custom search here. 

You can also visit the following web pages on different stuff in math. 

WORD PROBLEMS

HCF and LCM  word problems

Word problems on simple equations 

Word problems on linear equations 

Word problems on quadratic equations

Algebra word problems

Word problems on trains

Area and perimeter word problems

Word problems on direct variation and inverse variation 

Word problems on unit price

Word problems on unit rate 

Word problems on comparing rates

Converting customary units word problems 

Converting metric units word problems

Word problems on simple interest

Word problems on compound interest

Word problems on types of angles 

Complementary and supplementary angles word problems

Double facts word problems

Trigonometry word problems

Percentage word problems 

Profit and loss word problems 

Markup and markdown word problems 

Decimal word problems

Word problems on fractions

Word problems on mixed fractrions

One step equation word problems

Linear inequalities word problems

Ratio and proportion word problems

Time and work word problems

Word problems on sets and venn diagrams

Word problems on ages

Pythagorean theorem word problems

Percent of a number word problems

Word problems on constant speed

Word problems on average speed 

Word problems on sum of the angles of a triangle is 180 degree

OTHER TOPICS 

Profit and loss shortcuts

Percentage shortcuts

Times table shortcuts

Time, speed and distance shortcuts

Ratio and proportion shortcuts

Domain and range of rational functions

Domain and range of rational functions with holes

Graphing rational functions

Graphing rational functions with holes

Converting repeating decimals in to fractions

Decimal representation of rational numbers

Finding square root using long division

L.C.M method to solve time and work problems

Translating the word problems in to algebraic expressions

Remainder when 2 power 256 is divided by 17

Remainder when 17 power 23 is divided by 16

Sum of all three digit numbers divisible by 6

Sum of all three digit numbers divisible by 7

Sum of all three digit numbers divisible by 8

Sum of all three digit numbers formed using 1, 3, 4

Sum of all three four digit numbers formed with non zero digits

Sum of all three four digit numbers formed using 0, 1, 2, 3

Sum of all three four digit numbers formed using 1, 2, 5, 6