In the right triangle pqr, sin p = 0.8. what is the legth of rp?

PR is 10.

Sine is the ratio of the side opposite an angle to the hypotenuse. 0.8 is read as "eight tenths," so this would be 8/10.  We generally denote a right triangle using the letter of the right angle in the middle, so we will assume that Q is the right angle.  This means that PR is the hypotenuse.  Since sine = opposite/hypotenuse, sine = 8/10 means that the hypotenuse is 10.