Question

Raj tested his new flashlight by shining it on his bedroom wall. The beam of light can be described by the equation . How many inches wide is the beam of light on the wall?

Answer 1

Answer:

12 inches

Step-by-step explanation:

Raj tested his new flashlight by shinning it on his bedroom wall the beam of the light can be described by the equation (x^2-2x) + (y^2-4y) - 31=0. how many inches wide is the beam of light on the wall

Solution

Given:

(x^2-2x) + (y^2-4y) - 31=0

By completing the square

(x^2-2x) + (y^2-4y) - 31=0

(x^2-2x+1-1) + (y^2-4y+4-4)-31=0

(x-1)^2 -1 + (y-2)^2 - 4 - 31=0

(x-1)^2 + (y-2)^2 - 1 - 4 - 31=0

(x-1)^2 + (y-2)^2 - 36=0

(x-1)^2 + (y-2)^2=36

Writing the equation in the form: (x-h)^2+(y-k)^2=r^2

(x-1)^2+(y-2)^2=6^2

From the above, r=6

Where,

r=radius

how wide is the diameter ?

radius=6

Diameter= 2 × radius

=2×6

=12 inches