which
In plane trigonometry, the sine theorem or also known as the law of sines is a ratio between the lengths of the sides of a triangle and the sines of their corresponding opposite angles.
it is
![(a)/(\sin A)=(b)/(\sin B)](https://img.qammunity.org/2023/formulas/mathematics/college/sisbsbxxqz006gke6bfh2ny8zq9i7ddmkd.png)
According to the question Sin A=Sin B, so
![a=b](https://img.qammunity.org/2023/formulas/mathematics/college/xn0xizmefggxa7r71mt97cd4g855h5dt00.png)
wich means that this right traingle has two equal sides
if the two sides of a right triangle have the same length, then, they form the same angle with the hypotenuse
also, the question says that C=90 °
we know the sum of the internal angles on a triangle must be 180 °,then
![\begin{gathered} A+B+C=180 \\ A=B \\ 2A+C=180 \\ A=(180-C)/(2) \\ A=(90)/(2) \\ A=45\text{ \degree} \\ B=45\text{\degree} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/doeppq7vu2sefj0dbcpka4w2fmufbaqbl3.png)
so the answer is B)45 °