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MATH / Let A, B, C, and D be points on a circle. For each pair of points, we draw the line passing through the midpoint of those two points that is perpendicular to the line formed by the…
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problem
Let and be points on a circle. For each pair of points, we draw the line passing through the midpoint of those two points that is perpendicular to the line formed by the other two points. For example, we draw the line passing through the midpoint of that is perpendicular to line In this way, we draw a total of
$\binom{4}{2} = 6$ lines.
[asy]
unitsize(2.5 cm);
pair A, B, C, D, P;
pair[] M;
A = dir(118);
B = dir(62);
C = dir(323);
D = dir(165);
M[12] = (A + B)/2;
M[13] = (A + C)/2;
M[14] = (A + D)/2;
M[23] = (B + C)/2;
M[24] = (B + D)/2;
M[34] = (C + D)/2;
P = (A + B + C + D)/2;
draw(Circle((0,0),1),red);
draw(A--B,green);
draw(A--C,green);
draw(A--D,green);
draw(B--C,green);
draw(B--D,green);
draw(C--D,green);
draw(interp(M[12],P,-2)--interp(M[12],P,6),dashed);
draw(interp(M[13],P,-2)--interp(M[13],P,2),dashed);
draw(interp(M[14],P,-0.5)--interp(M[14],P,2.5),dashed);
draw(interp(M[23],P,-0.7)--interp(M[23],P,1.5),dashed);
draw(interp(M[24],P,-3.3)--interp(M[24],P,4),dashed);
draw(interp(M[34],P,-0.3)--interp(M[34],P,1.6),dashed);
dot("", A, A);
dot("", B, B);
dot("", C, C);
dot("", D, D);
dot(M[12]);
dot(M[13]);
dot(M[14]);
dot(M[23]);
dot(M[24]);
dot(M[34]);
[/asy]
It turns out that all six lines will always pass through the same point, say There exist constants and such that can always be expressed in the form
Find Plain-text mathematical notation (without MathML)
Let A, B, C, and D be points on a circle. For each pair of points, we draw the line passing through the midpoint of those two points that is perpendicular to the line formed by the other two points. For example, we draw the line passing through the midpoint of (AB)¯ that is perpendicular to line CD. In this way, we draw a total of $\binom{4}{2} = 6$ lines.
[asy]
unitsize(2.5 cm);
pair A, B, C, D, P;
pair[] M;
A = dir(118);
B = dir(62);
C = dir(323);
D = dir(165);
M[12] = (A + B)/2;
M[13] = (A + C)/2;
M[14] = (A + D)/2;
M[23] = (B + C)/2;
M[24] = (B + D)/2;
M[34] = (C + D)/2;
P = (A + B + C + D)/2;
draw(Circle((0,0),1),red);
draw(A--B,green);
draw(A--C,green);
draw(A--D,green);
draw(B--C,green);
draw(B--D,green);
draw(C--D,green);
draw(interp(M[12],P,-2)--interp(M[12],P,6),dashed);
draw(interp(M[13],P,-2)--interp(M[13],P,2),dashed);
draw(interp(M[14],P,-0.5)--interp(M[14],P,2.5),dashed);
draw(interp(M[23],P,-0.7)--interp(M[23],P,1.5),dashed);
draw(interp(M[24],P,-3.3)--interp(M[24],P,4),dashed);
draw(interp(M[34],P,-0.3)--interp(M[34],P,1.6),dashed);
dot("A", A, A);
dot("B", B, B);
dot("C", C, C);
dot("D", D, D);
dot(M[12]);
dot(M[13]);
dot(M[14]);
dot(M[23]);
dot(M[24]);
dot(M[34]);
[/asy]
It turns out that all six lines will always pass through the same point, say P. There exist constants a, b, c, and d such that (P)→ can always be expressed in the form
(P)→=a(A)→+b(B)→+c(C)→+d(D)→.Find a+b+c+d.Original LaTeX notation
Let $A,$ $B,$ $C,$ and $D$ be points on a circle. For each pair of points, we draw the line passing through the midpoint of those two points that is perpendicular to the line formed by the other two points. For example, we draw the line passing through the midpoint of $\overline{AB}$ that is perpendicular to line $CD.$ In this way, we draw a total of $\binom{4}{2} = 6$ lines.
[asy]
unitsize(2.5 cm);
pair A, B, C, D, P;
pair[] M;
A = dir(118);
B = dir(62);
C = dir(323);
D = dir(165);
M[12] = (A + B)/2;
M[13] = (A + C)/2;
M[14] = (A + D)/2;
M[23] = (B + C)/2;
M[24] = (B + D)/2;
M[34] = (C + D)/2;
P = (A + B + C + D)/2;
draw(Circle((0,0),1),red);
draw(A--B,green);
draw(A--C,green);
draw(A--D,green);
draw(B--C,green);
draw(B--D,green);
draw(C--D,green);
draw(interp(M[12],P,-2)--interp(M[12],P,6),dashed);
draw(interp(M[13],P,-2)--interp(M[13],P,2),dashed);
draw(interp(M[14],P,-0.5)--interp(M[14],P,2.5),dashed);
draw(interp(M[23],P,-0.7)--interp(M[23],P,1.5),dashed);
draw(interp(M[24],P,-3.3)--interp(M[24],P,4),dashed);
draw(interp(M[34],P,-0.3)--interp(M[34],P,1.6),dashed);
dot("$A$", A, A);
dot("$B$", B, B);
dot("$C$", C, C);
dot("$D$", D, D);
dot(M[12]);
dot(M[13]);
dot(M[14]);
dot(M[23]);
dot(M[24]);
dot(M[34]);
[/asy]
It turns out that all six lines will always pass through the same point, say $P.$ There exist constants $a,$ $b,$ $c,$ and $d$ such that $\overrightarrow{P}$ can always be expressed in the form
\[\overrightarrow{P} = a \overrightarrow{A} + b \overrightarrow{B} + c \overrightarrow{C} + d \overrightarrow{D}.\]Find $a + b + c + d.$level
Level 4
type
Precalculus
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