In right triangle DEF, it is known that Cos D = (12/13) and Cos F = (5/13). If FD = 39, then DE = ? Hint, draw the right triangle.

The radius of the circle is 4 cm and the measure of the central angle is 90° the area of the sector with a central angle measuring 90° and radius of length 4 cm is vt cm the triangle in the sector is 4 cm the area of the triangle is v/cm² the area of the segment of the circle is (471 - ) cm?

The difference of three and the reciprocal of a number is equal to the quotient of 20 and the number. find the number.

I'm at a bookstore with $\$35$ in my pocket and a $20\%$-off coupon. what is the cost of the most expensive book i can buy with my money and the coupon? (assume that there are books of every possible price in the bookstore. it's a large bookstore! )