The angle \theta_1θ
1
​ theta, start subscript, 1, end subscript is located in Quadrant \text{I}Istart text, I, I, I, end text, and \cos(\theta_1)=-\dfrac{13}{15}cos(θ
1
​ )=−
15
13
​ cosine, left parenthesis, theta, start subscript, 1, end subscript, right parenthesis, equals, minus, start fraction, 13, divided by, 15, end fraction .
What is the value of \sin(\theta_1)sin(θ
1
​ )sine, left parenthesis, theta, start subscript, 1, end subscript, right parenthesis?