Question

A small radio transmitter broadcasts in a 53 mile radius. If you drive along a straight line from a city 70 miles north of the transmitter to a second city 74 miles east of the transmitter, during how much of the drive will you pick up a signal from the transmitter?

Answer 1

Answer:

29% of the drive

Step-by-step explanation:

The plot of the problem is:

Transmitter at origin (0,0)  

City to the north at (0,70)

City to the east at (74,0)

The path from city to city is a line with slope:

m = (-70)/74 = -35/37

and y-intercept at y = 70, so the equation is y = (-35/37)*x + 70.

The transmitter reach the area enclosed by the next circle:

x^2 + y^2 = 53^2

See the picture attached

The intersection is gotten from the picture or solving:

x^2 + [(-35/37)*x + 70]^2 = 53^2

the points approximately are: (24.1, 47.2) and (45.8, 26.7)

From Pythagorean theorem the total distance of the trip is:

d1 = √(70^2 + 74^2) ≈ 101.9 miles

And the distance when the signal is picked up is:

d2 =√ [(45.8 - 24.1)^2 + (47.2 - 26.7)^2] ≈ 29.9 miles

You will pick up a signal from the transmitter in (d2/d1)*100 = 29% of the drive.