Displacement equation is given by y(t)=A sin(wt+ ϕ) but in some books y(t)= A cos(wt+ ϕ) . i know both these function are periodic so they are defining motion .but mine question is how one can define a one type of motion by two different trigonometric terms sine and cosine if you see sine and cosine is having different values for different angles then how one a displacement of pendulum by sine and cosine both …? and in numerical also sometime we are using cosine term and some time sine how we comes to know that this equation we have to use for this sum …Pls answer me

Asked Solanki Bakul