What was the surface area in cm2 that the main beam covered when the flashlight was held at a 90°angle?

Explanation:

This type of question can be approached  experimentally; so , what we are going to do here will be detailed discussion of how to go about with the experiment. So to start with;

We will need a flashlight, a flashlight holder , a protractor and a ruler.

The first step is to place the flashlight holder on a flat surface and attach

the flashlight to the holder.

From the question; the angle given is  90°

SO; we will position the flashlight at a 90° angle; by doing so , the light rays will be directed in a rectilinear position to the surface area.

To determine the angle of incidence that the main beam covered , we use a protractor to determine that.

Lastly; The surface area in cm² is determined by the use of the ruler to measure the surface area that is covered by the light rays.

Precaution: It is advisable to dim the light in the room prior to turning on the flashlight in order to avoid error due to parallax.

+15-35=-20

going in opposite directions

pythagoras' theorem

square root (-5^2+9^2)

square root (25+81)

square root (106)

angle is tan^-1(9/5)

neg x, pos y