Answer:
Step-by-step explanation:
AM is perpendicular to BD because they from a right angle and the definition of perpendicular is when two lines meet they form a right angle. AM goes straight down and BD form the horizontal line. These two lines form a right angle so AM is perpendicular to BD.
OK, so the graph is a parabola, with points x=0,y=0; x=6,y=-9; and x=12,y=0
Because the roots of the equation are 0 and 12, we know the formula is therefore of the form
y = ax(x - 12), for some a
So put in x = 6
-9 = 6a(-6)
9 = 36a
a = 1/4
So the parabola has a curve y = x(x-12) / 4, which can also be written y = 0.25x² - 3x
The gradient of this is dy/dx = 0.5x - 3
The key property of a parabolic dish is that it focuses radio waves travelling parallel to the y axis to a single point. So we should arrive at the same focal point no matter what point we chose to look at. So we can pick any point we like - e.g. the point x = 4, y = -8
Gradient of the parabolic mirror at x = 4 is -1
So the gradient of the normal to the mirror at x = 4 is therefore 1.
Radio waves initially travelling vertically downwards are reflected about the normal - which has a gradient of 1, so they're reflected so that they are travelling horizontally. So they arrive parallel to the y axis, and leave parallel to the x axis.
So the focal point is at y = -8, i.e. 1 metre above the back of the dish.
Answer:3.42
Step-by-step explanation:to get the answer to a area equation you need to multiply the length by the width.
X=6 is the answer for the problem
Solution:
Let me define pyramid first.A pyramid is a Polyhedron , whose base can be any polygon and it's faces are triangular which meet at a point called vertex.
Volume of Pyramid =
Side of base which is an equilateral triangle= 4 cm
Area of whole pyramid = 12 square cm
Area of Equilateral triangle having side 4 cm= cm²
So, Area of three triangle which are faces of pyramid = (12 - 4 √3)cm²
Area of triangle =
12 - 4 √3=
Height =
Height=(6-2√3) cm
Volume of pyramid = Area of Equilateral triangle which is it's Base × Height of Pyramid
=4√3 × (6-2√3) cm³
=(24 √3 -24)
= 24 (1.732-1)
=24 × 0.732
=17.568 cm³