Calculate the distance of the line to the origin.
y=43x−5
Für diese Aufgabe benötigst Du folgendes Grundwissen: Slope/Gradient of a line
The shortest connection of any point on the line g(x):y=m1⋅x+b to the origin is a second line h(x):y=m2⋅x+b2 which passes through the origin and is perpendicular to g.
Passing through the origin means h(0)=b2=0.
Being perpendicular means
m2=−m11
Plug in the known value of m1.
m2=−431=−34
So the perpendicular line has the line equation h(x):y=−34x.
Now calculate the intersection point A(xs∣ys) of the two lines by setting equal their line equations.
g(xs) = h(xs) ↓ Plug in the line equations.
−34xs = 43xs−5 −43xs ↓ Get the variable xs on the left side
−1225xs = −5 ⋅(−1) 1225xs = 5 :1225 xs = 512 = 2.4 Now substitute xs into one of the line equations to determine ys.
h(xs):ys=−34xs
Plug in xs=2.4 .
ys=−34⋅2.4=−3.2
The intersection of the lines h and g is therefore at A(2.4∣−3.2).
Now determine the distance of the origin to the calculated intersection point A, this is exactly the shortest distance of the line g to the origin.
d=(xs−x0)2+(ys−y0)2
Plug in the values.
d=(2.4−0)2+(−3.2−0)2
Simplify.
=5.76+10.24=16=4
The shortest distance of the line g to the origin is therefore 4.
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y=−21x+2
Für diese Aufgabe benötigst Du folgendes Grundwissen: Slope/Gradient of a line
The shortest connection of any point on the line g(x):y=m1⋅x+b to the origin is a second line h(x):y=m2⋅x+b2 which passes through the origin and is perpendicular to g.
Passing through the origin means h(0)=b2=0.
Being perpendicular means
m2=−m11
Plug in the known value of m1.
m2=−−211=2
So the perpendicular line has the line equation h(x):y=2x.
Now calculate the intersection point A(xs∣ys) of the two lines by setting equal their line equations.
g(xs) = h(xs) ↓ Plug in the line equations.
−21xs+2 = 2xs −2xs ↓ Get the variable xs on the left side
−2.5xs+2 = 0 −2 ↓ Get the 2 to the right side.
−2.5xs = −2 :(−2.5) xs = 0.8 Now substitute xs into one of the line equations to determine ys.
h(xs):ys=2xs
Plug in xs=0.8 .
ys=2⋅0.8=1.6
The intersection of the lines h and g is therefore at A(0.8∣1.6).
Now determine the distance of the origin to the calculated intersection point A, this is exactly the shortest distance of the line g to the origin.
d=(xs−x0)2+(ys−y0)2
Plug in the values.
d=(0.8−0)2+(1.6−0)2
Simplify.
=0.64+2.56=3.2≈1.79
The shortest distance of the line g to the origin is therefore approximately 1.79.
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