If a persons use of cigerattes increases, then the persons lung function will decrease because the chemicals in cigarettes damage lung tissue and make it difficult to breathe. q: the independent variable is : the dependent variable

1) use of cigarettes

2) lung function

Explanation:

The variable that we can change or which can be controled is treated as the independent variable.

The variable that we cannot change or which is being controlled by the independent variable is called as the dependent variable.

In this case the thing we can control is use of cigarettes, not the lung function. So use of cigarettes is the independent variable

Lung function is something we cannot directly control. ( can be controlled by medicine and exercises but not in the same way as use of cigarettes) So lung function is to be taken as dependent variable.

54 degrees incident angle = reflected angle

angle is from normal turned to line of ray