The correct option is A 10 cm
Here, x=5√2(sin2πt+cos2πt)
⇒x=5√2sin2πt+5√2cos2πt ...(i)
The standard equation of simple harmonic motion is given by
x=A1sinωt+A2cosωt ...(ii)
Now, comparing Eqs. (i) and (ii), we obtain
A1=√A21+A22=√(5√2)2+(5√2)2
=√50+50
=10cm