Light Bounce

The link above will open a new window/tab to an online applet game. The game involves aiming a laser pointer (P), which is 225 cm above the floor, at a mirror (M), which is 100 cm from the wall.

The equation relating the height of the reflection on the wall (y) as a function of pointer distance (x) from the wall is: y = twenty-one thousand six-hundred over x minus two 21600 x − 2 + 10

Find the height of the reflection on the wall when the pointer is a distance of 325 cm from the wall in three ways:

• First, use substitution and find the height algebraically.
• Then, enter the equation into your graphing calculator and find the height in the table.
• Next, adjust the window setting on your calculator and use the Trace feature to verify the height.
• Finally, go to the website and set the conditions for the situation on the Light Bounce tool and confirm the height of the reflection.

Find the distance that the laser pointer was from the wall when the height of the reflection is 76 cm in three ways.

• First, use substitution and solve the equation algebraically.
• Then, enter the equation into your graphing calculator and find the distance in the table.
• Next, enter the height into the graphing calculator as a second equation and use the intersect feature to verify the distance of the laser from the wall.
• Finally, go to the website and set the conditions for this situation on the Light Bounce tool and confirm the distance that the laser must be from the wall to have a reflection height of 76 cm.

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Check Your Answer

Algebraically:

76 = twenty-one thousand six-hundred over x minus one-hundred 21600 x − 100 + 10; 66 = twenty-one thousand six-hundred over x minus one-hundred 21600 x − 100 ; 66x − 6600 = 21600; 66x = 28200; x = 427.27