Answer:
BD = 4.99 units
Step-by-step explanation:
Consider the triangle ABD only.
The angle formed is 31 degrees which occurs between two sides that are AD and BC.
We know that for a right angled triangle, the angle can always be taken as an angle between hypotenuse and base.
Thus, The perpendicular sides is then 3 units, where base is BD and Hypotenuse is AD
Using formula for tanθ
tanθ = Perpendicular/Base
tan31 = 3/BD
0.601 = 3/BD
BD = 3/0.601
BD = 4.99 units
The +5 because that's the y value on the graph
40 tens = how many hundreds. 40 x 10 = 400
(a) 4
(b) y = sqrt(9 - (9/16)x^2)
The best guess to the formula using knowledge of the general formula for an ellipse is:
x^2/16 + y^2/9 = 1
(a). An ellipse is reflectively symmetrical across both the major and minor axis. So if you can get the area of the ellipse in a quadrant, then multiplying that area by 4 would give the total area of the ellipse. So the factor of 4 is correct.
(b). The general equation for an ellipse is not suitable for a general function since it returns 2 y values for every x value. But if we restrict ourselves to just the positive value of a square root, that problem is easy to solve. So let's do so:
x^2/16 + y^2/9 = 1
x^2/16 + y^2/9 - 1 = 0
x^2/16 - 1 = - y^2/9
-(9/16)x^2 + 9 = y^2
9 - (9/16)x^2 = y^2
sqrt(9 - (9/16)x^2) = y
y = sqrt(9 - (9/16)x^2)
