Question

Find the area of the rectangle shown in the figure.

length = radical (3) + radical (5)
width = radical (3) + radical (5)

My answer: a= 8 + 2 radical (15)
or
a = 15.75

agree, you seem to be able to do these

should i leave it as the radical form or the decimal form which is more appropriate

The radical form is the "exact" answer, while the decimal is an approximation.

The textbook or the teacher should have instructed you which way it should be answered.
Both ways are valid


thank you.