Anna is going to play guitar in her school's annual concert. if she starts by practicing for one hour per day and increases the time by 30 minutes each day, how long will she practice on the seventh day?

answer:  

step-by-step explanation:

here x represents the height of the pole,

and, the height of the shadow of the pole is 12 feet.

also, the angle of elevation from the top of the pole is 40°,

therefore,

by the low of sine,

which is the required equation for finding the value of x,