Find cosθ+cos3θ+cos5θ+cos7θ by using the Sum-to-Product Formula. Please also show your work as well. Thanks!

Can someone, me with this.i really need with this

What is the surface area of the sphere?

The equatorial radius of earth is approximately 6 × 10^3 km, while the equatorial radius of saturn is approximately 6 × 10^4 km. which of the following is true? a. the equatorial radius of saturn is approximately one hundred times that of earth. b. the equatorial radius of saturn is approximately ten times that of earth. c. the equatorial radius of earth is approximately one hundred times that of saturn. d. the equatorial radius of earth is approximately ten times that of saturn.