Kropka143
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Określ odległość punktu P=(2,0) od prostej -3x-4y-44=0



Odpowiedź :

-3x - 4y - 44 = -

-4y = 3x + 44

y = (-3/4)x - 11

y₂ = a₂x + b

a₂ = -1/a

a₂ = -1/(-3/4)

a₂ = 4/3

y = (4/3)x + b ; P(2;0)

0 = (4/3)*2 + b

0 = 8/3 + b

b = -8/3

y = (4/3)x - 8/3

[tex]\left \{ {{y = \frac{4}{3} x - \frac{8}{3} } \atop {y = -\frac{3}{4} x - 11}} \right. \\\left \{ {{y = \frac{4}{3} x - \frac{8}{3} } \atop {\frac{4}{3} x - \frac{8}{3} = -\frac{3}{4} x - 11}} \right. \\\left \{ {{y = \frac{4}{3} x - \frac{8}{3} } \atop { \frac{4}{3} x +\frac{3}{4} x = - 11+ \frac{8}{3}}} \right.\\\left \{ {{y = \frac{4}{3}x - \frac{8}{3}} \atop {\frac{16}{12}x +\frac{9}{12}x= - \frac{33}{3} +\frac{8}{3} }} \right.[/tex]

[tex]\left \{ {{y = \frac{4}{3}x - \frac{8}{3}} \atop {\frac{25}{12}x = - \frac{25}{3} }} \right.\\\left \{ {{y = \frac{4}{3}x - \frac{8}{3}} \atop {x = - \frac{25}{3}*\frac{12}{25} }} \right.\\\left \{ {{y = \frac{4}{3}x - \frac{8}{3}} \atop {x = - 4 }} \right.\\\left \{ {{y = \frac{4}{3}*(-4) - \frac{8}{3}} \atop {x = - 4 }} \right.\\\left \{ {{y = -\frac{16}{3} - \frac{8}{3}} \atop {x = - 4 }} \right.\\\left \{ {{y = -\frac{24}{3}} \atop {x = - 4 }} \right.\\[/tex]

[tex]\left \{ {{y = -8} \atop {x = - 4 }} \right.[/tex]

punkt należący do prostej y: P₂ = (-4;-8)

[tex]|PP_{2}| = \sqrt{(-4-2)^{2}+(-8-0)^{2}} = \sqrt{(-6)^{2} + (-8)^{2}}= \sqrt{36 + 64} = \sqrt{100} = 10[/tex]

Odp: Odległosć punktu P(2,0) od prostej -3x-4y-44=0, jest równa 10.