Q6 q19.) write the expression as the sine, cosine, or tangent of an angle. then find the exact value of the expression.

Using sin(A+B) = sinAcosB + cosAsinB

sin20cos40 + cos20sin40 = sin(20+40) = sin60degree

= 

The function f(x) = 5(0.8)x is located in the first quadrant, forming a increasing curve. Imagine the reflection of the graph of the function. It is located in the fourth quadrant, forming a decreasing curve.

The graph that shows reflection is just the negative of the function. So the answer is (x) = –5(0.8)x