Use Identities to Find the Exact Value $\mathrm { a } = 15 | \sec 2 \pi \mathrm { t } |$

Use Identities to find the exact value.
-A rotating beacon is located 15 ft from a wall. The distance from the beacon to the point on the wall where the beacon is aimed is given by $\mathrm { a } = 15 | \sec 2 \pi \mathrm { t } |$ ,
where $t$ is time measured in seconds since the beacon started rotating. Find a for $t = 0.42$ seconds. Round your answer to the nearest hundredth.

A) $38.72 \mathrm { ft }$
B) $60.32 \mathrm { ft }$
C) $- 17.12 \mathrm { ft }$
D) $17.12 \mathrm { ft }$