# Thread: Is shooting at this angle accurate?

1. ## Is shooting at this angle accurate?

I got lasered yesterday (and saved by my LP905) from what I think is quite an angle. I was heading north on a two lane divided highway (4 lanes total north and south combined) and got lasered from an leo standing off the shoulder of the opposite side of the highway. The median is about 4 lanes wide so I would guess he was approx 80-100 feet sideways distance from my car as I passed by. I know at a greater distance the angle is much less. Where is the limit in terms of accuracy? I assume he was shooting a PL3 because that is all I've seen here in WA.

2. ## Re: Is shooting at this angle accurate?

Originally Posted by jsillars
I got lasered yesterday (and saved by my LP905) from what I think is quite an angle. I was heading north on a two lane divided highway (4 lanes total north and south combined) and got lasered from an leo standing off the shoulder of the opposite side of the highway. The median is about 4 lanes wide so I would guess he was approx 80-100 feet sideways distance from my car as I passed by. I know at a greater distance the angle is much less. Where is the limit in terms of accuracy? I assume he was shooting a PL3 because that is all I've seen here in WA.
I would say it would be an accurate reading as far as the right car but the speed would be off by I am guessing -2 to -5mph.

3. If you want to get it exactly do the following.

Compute the angle of the beam to your direction of travel. You can find this by taking the arc tangent X/L where L is the distance you are from being directly opposite the LEO when he is shooting and X is the distance to the side of the LEO.

In your case you stated he was 80-100 feet to the side. I'll take a guess and say he shot you when L was 1000 feet. Then the arc tangent of 90/1000 is 5.14 degrees.

You can now find the component of your velocity in the direction of the LIDAR beam by taking the cosine of the angle and multiplying it by your speed. In this example the LEO would read cosine(5.14 degrees) x your speed or .9959 times your actual speed. If he shot you at 500 feet then his reading would be the cosine(arc tangent(90/500) times your speed or .9841 times your actual speed.

As you can see not sleeping through the whole semester in high school trig class did actually result in something marginally useful.

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