Right Triangle = 90°
Giving the angles 45°, you can find the value of X by using 12 (the opposite side from the angle 45°).
[tex]sin(theta) = \frac{opposite}{hypotenuse} [/tex]
theta means angle
[tex] \sin(45) = \frac{12}{x} [/tex]
Cross multiple
[tex] \sin(45)x = 12
Divide by sin(45) on both side
x= \frac{12}{sin(45)} [/tex]
