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Triangles: Calculating Orthocentre, Circumcentre, Centroid? I need help ASAP?
I need to CALCULATE the Orthocentre, Circumcentre, Centroid of a triangle with the points at A(0,24) B (-15,0) and C (24,0).
I've been trying this for a long time and I still don't understand it. I tried looking elsewhere for help but everywhere I've tried I just get more confused. I'd appreciate it if someone could help me solve this as soon as possible, preferably within the next 45-60 minutes. Thanks.
PS: As far as I know, the slopes are mAB: 8/5 mBC: 0/39 mAC: -24/24 but I don't know where to go from there.
Please show the steps that you have to do to get there so I can learn for the next time I get a question like this, not just the answer. :)
2 Answers
- ?Lv 61 decade agoFavorite Answer
(i) Centroid:
Centroid of the triangle formed by (a1,b1), (a2,b2), (a3,b3) is ( (a1+a2+a3)/3, (b1+b2+b3)/3 ).
Hence the centroid is: ( (0-15+24)/3, (24+0+0)/3 ) = (3,8).
(ii) Orthocenter
Orthocenter is the intersection of altitudes.
m(BC) = 0/39 = 0 which is parallel to the x-axis. So the altitude through A(0,24) is parallel to the y-axis, the equation is: y=24.
m(AC) = -24/24 = -1. So the altitude through B(-15,0) has a slope of 1, the equation is: y = x+15
The orthocenter is the intersection of the lines y=24 and y=x+15. Substitute y=24 to y=x+15, we get x=9. So the orthocenter is (9,24).
(iii) Circumcenter
Label the circumcenter, centroid, and orthocenter by O, G, H, respectively.
O, G, H lies on Euler line in that order, such that OG = 2GH. So O = (G+2H)/3:
( (3+2*9)/3, (8+2*24)/3 ) = (7, 56/3).
Source(s): http://en.wikipedia.org/wiki/Euler_line - ?Lv 44 years ago
do you elect geometric or algebraic ideas? eg: if given which you have co-ordinates of three factors, A, B, C, forming vertices of a triangle, the centroid is at (A+B+C)/3; yet do you have the co-ordinates? if no longer, map them as A=(0,0), B=(x[b],0), C=(x[c],y[c]). then centroid = (A+B+C)/3 = ( (x[b]+x[c])/3, y[c]/3 ). if the circumcentre is at (u,v), then factors A,B,C are all on the circle defined by skill of (x-u)² + (y-v)² = R² that's undemanding to confirm as quickly as you have got here across it. (x[a]-u)² + (y[a]-v)² = (x[b]-u)² + (y[b]-v)² = (x[c]-u)² + (y[c]-v)² = R² yet whilst A=(0,0), as above, then (0-u)² + (0-v)² = (x[b]-u)² + (0-v)² = (x[c]-u)² + (y[c]-v)² = R² the orthocentre is slightly extra officious. yet examine the wikipedia internet site for some information approximately it, additionally. this is got here across by skill of extending perpendicular lines from the perimeters, and finding one that passes in the path of the different vertex. algebraically, those extensions have the optimum pass-product with the corresponding edges; you could hire a co-ordinate shift to discover that line. eg: for line BC, its line is defined by skill of B + ok(C-B) = ( ok(x[c]-x[b])+x[b], ky[c] ); and the set of all perpendicular lines is then defined by skill of ( hy[c] +e, h(x[c]-x[b])+x[b] +f) for some constants e,f. if (e,f) is on the line BC, then the only that intersects A is unique. x[a] = hy[c] +e y[a] = h(x[c]-x[b])+x[b] +f provided that (e,f) is online BC, x[a] = hy[c] +ok(x[c]-x[b])+x[b]; and y[a] = h(x[c]-x[b])+x[b] + ky[c] yet whilst A=(0,0), as above, then the line will fulfill those equations... 0 = kx[c] + hy[c] + x[b](a million-ok); and 0 = hx[c] + ky[c] + x[b](a million-h). the different 2 lines are got here across in addition; the orthocentre then meets at their intersection. yet i'm actually sympathetic to what you're announcing approximately calculation errors.