Which equation is perpendicular to 3x - y = 9 and goes through the point (6,6)
1 answer:
Answer:
y = - x + 8
Step-by-step explanation:
The equation of a line in slope- intercept form is
y = mx + c ( m is the slope and c the y- intercept )
Rearrange 3x - y = 9 into this form by subtracting 3x from both sides
- y = - 3x + 9 ( divide all terms by - 1 )
y = 3x - 9 ← in slope- intercept form
with slope m = 3
Given a line with slope m then the slope of a line perpendicular to it is
= -
= -
, thus
y = - x + c ← is the partial equation
To find c substitute (6, 6) into the partial equation
6 = - 2 + c ⇒ c = 6 + 2 = 8
y = - x + 8 ← equation of perpendicular line
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9514 1404 393
Answer:
8√3 ≈ 13.86 ft
Step-by-step explanation:
The light source is usually placed at the focus, so the focus-vertex distance is p=3 ft. The equation for the parabola with its vertex at the origin is ...
y = 1/(4p)x^2
y = 1/12x^2
The opening for some y-value extends ±x from the axis of symmetry, so is a total of 2x in width.
For y=4, the corresponding value of x is ...
4 = 1/12x^2
48 = x^2
√48 = x = 4√3
Then the width of the searchlight opening is ...
2(4√3 ft) = 8√3 ft ≈ 13.86 ft
