Answer
Auto A: 68.94 mph
Auto B: 65.78 mph
Work Step by Step
To find the radar speed reading we multiply the actual speed and the $\cos$ of the angle.
Auto A
Actual Speed: 70 mph
Angle: 10$^{\circ}$
Radar Reading = $R$$_{a}$
Therefore:
$R$$_{a}$ = 70 $\cos$ 10$^{\circ}$
$R$$_{a}$ = 68.94 mph
Auto B
Actual Speed: 70 mph
Angle: 20$^{\circ}$
Radar Reading = $R$$_{b}$
Therefore:
$R$$_{b}$ = 70 $\cos$ 20$^{\circ}$
$R$$_{b}$ = 65.78 mph
