一簡(jiǎn)諧波沿x軸正向傳播,波長λ=4m,周期T=4s,已知x=0處的質(zhì)點(diǎn)的振動(dòng)曲線如圖所示. (1)寫出時(shí)x=0處質(zhì)點(diǎn)的振動(dòng)方程; (2)寫出波的表達(dá)式; (3)畫出t=1s時(shí)刻的波形曲線.