What is the length x of the side of the triangle below? (Hint: use the cosine function.)
A. 9.1
B. 9.7
C. 4.7
D. 4.2

With i really need the correct answer!

How is sound energy produced a. vibrating objects b. objects being heated c. temperature differences d. stationary objects

Select all the correct answers. which changes will increase the rate of reaction during combustion? decreasing the area of contact between the reactants adding more oxygen to the reaction removing heat from the reaction changing the reactants from solid form to powdered form lowering the exposure of the reactants to air