Suppose x=9 tan (theta) and the angle (theta) is in the first quadrant. write algebraic expressions for sin (theta) and cos (theta) and in terms of x .

The tangent trigonometric function is equal to the  quotient of sine and cosine through the trigonometric identity. In this case, we are given with x = 9 tan (theta). Hence the answer to this problem is the expounded algebraic expression x = 9 sin (theta) / cos (theta).