The Superposition of Two Waves And , Results in a Wave with a Frequency of
A)85

The superposition of two waves, $$y _ { 1 } = \left( 2 \times 10 ^ { - 8 } \mathrm {~m} \right) \sin \left[ \pi \left( \frac { x } { 2 \mathrm {~m} } - \frac { 170 } { \mathrm {~s} } t \right) \right]$$ and $$y _ { 2 } = \left( 2 \times 10 ^ { - 8 } \mathrm {~m} \right) \sin \left[ \pi \left( \frac { x } { 2 \mathrm {~m} } - \frac { 170 } { \mathrm {~s} } t - \frac { 1 } { 2 } \right) \right]$$ , results in a wave with a frequency of

A) 85 Hz.
B) 170 Hz.
C) 85 $\pi$ Hz.
D) 340 Hz.
E) 170 $\pi$ Hz.