Can you help with this, I don't know how to do it

Answer:
105 sqrt(2) =x
Step-by-step explanation:
Since this is a right triangle we can use trig functions
so sin theta = opposite side/hypotenuse
sin 45 = x/210
Multiply each side by 210
210 sin 45 = x
We know sin 45 = sqrt(2)/2
210 * sqrt(2)/2 = x
105 sqrt(2) =x
Answer:
B
Step-by-step explanation:
Using trig ratios
sin(45) = opposite/hypotenuse
sin(45) = x/210
sqrt(2)/2 = x/210
x = 210sqrt(2)/2
x = 105sqrt(2)