Work out the legnth of x sides 14cm and 7cm

How do i work this problem out using the equation a=pe^rt

The random variable x is the number of occurrences of an event over an interval of ten minutes. it can be assumed that the probability of an occurrence is the same in any two-time periods of an equal length. it is known that the mean number of occurrences in ten minutes is 5.3. the appropriate probability distribution for the random variable

The trigonometric ratios sine and secant are reciprocals of each other