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## Homework Statement

Two sinusoidal waves in a string are defined by the

functions

y1 " (2.00 cm) sin(20.0x # 32.0t)

and

y2 " (2.00 cm) sin(25.0x # 40.0t)

where y1, y2, and x are in centimeters and t is in seconds.

(a) What is the phase difference between these two waves

at the point x " 5.00 cm at t " 2.00 s?

**(b) What is the positive**

x value closest to the origin for which the two phases

differ by (& at t " 2.00 s? (This is where the two waves

add to zero.)

x value closest to the origin for which the two phases

differ by (& at t " 2.00 s? (This is where the two waves

add to zero.)

## The Attempt at a Solution

My teacher went over this problem and gave us this answer...

-5x+16= +3.14 ->

**X=2.57cm**-> choose this answer because it is closest to the origin

-5x+16= -3.14 -> X=3.83cm

book answer is

**X=.0584**

He mentioned why it was different, but I could not understand what he said... he mumbles a lot... lol.