15.3. The lenth of side x of the right triangle in the image is 15.3.
To solve this problem we have to use trigonometric reasons and the equation tan θ = side opposite/side adjacent. From the right triangle of the image we know that the side opposite is 10 and side adjacent is x, with θ = 25°.
tan 25° = 10/x
Clearing x from the equation above:
x = arctan 25° (10)
x = 15.308