A year ago, I posted this problem on [MSE]. Now I have edit the following similar problem.(To adopt Hjalmar Rosengren suggestion)

Which rarional values of $c$ and $d$,the numbers $\sin{(\pi\cdot c)},\sin{(\pi\cdot d)}$ and $1$ are linearly dependent over $Q$

Question 1: case 1: when $d=\dfrac{1}{18}$,How prove this $c=\dfrac{1}{18}?$

Question 2 case 2: when $d\in Q$ give numbers,I guess also $c=d?$

because the case $d=0$ is known as Niven's Theorem