A triangle has corners at (2 ,4 )(2,4), (6 ,5 )(6,5), and (4 ,3 )(4,3). What is the area of the triangle's circumscribed circle?

1 Answer
Jun 21, 2017

The area is =14.84u^2=14.84u2

Explanation:

To calculate the area of the circle, we must calculate the radius rr of the circle

Let the center of the circle be O=(a,b)O=(a,b)

Then,

(2-a)^2+(4-b)^2=r^2(2a)2+(4b)2=r2.......(1)(1)

(6-a)^2+(5-b)^2=r^2(6a)2+(5b)2=r2..........(2)(2)

(4-a)^2+(3-b)^2=r^2(4a)2+(3b)2=r2.........(3)(3)

We have 33 equations with 33 unknowns

From (1)(1) and (2)(2), we get

4-4a+a^2+16-8b+b^2=36-12a+a^2+25-10b+b^244a+a2+168b+b2=3612a+a2+2510b+b2

8a+2b=418a+2b=41.............(4)(4)

From (2)(2) and (3)(3), we get

36-12a+a^2+25-10b+b^2=16-8a+a^2+9-6b+b^23612a+a2+2510b+b2=168a+a2+96b+b2

4a+4b=364a+4b=36

a+b=9a+b=9..............(5)(5)

From equations (4)(4) and (5)(5), we get

(41-2b)/8=9-b412b8=9b

41-2b=72-8b412b=728b

6b=72-416b=7241, =>, b=31/6b=316

8a=41-2*31/6=41-31/3=92/38a=412316=41313=923, =>, a=23/6a=236

The center of the circle is =(23/6,31/6)=(236,316)

r^2=(2-23/6)^2+(4-31/6)^2=(-11/6)^2+(-7/6)^2r2=(2236)2+(4316)2=(116)2+(76)2

=170/36=17036

=85/18=8518

The area of the circle is

A=pi*r^2=85/18*pi=14.84A=πr2=8518π=14.84