1. The problem statement, all variables and given/known data The gravitational acceleration at latitude x (0<x<90) can be estimated with g(x)=a*cos(2x)+b. 1) Determine what a and b is if the gravitational acceleration is 9.780m/s^2 at x=0 and 9.832m/s^2 at x=90. 2. Relevant equations 3. The attempt at a solution So I begin by entering what I know: 9.780=a+b (Because cos(2*0) is 1) 9.780-a=b And then the other equation: 9.832=-5.9846*a+b (Because cos(2*90) is -5.9846) I then combine the two equations, jumping over the middle steps, gives: -0.00868=a-a which means... -0.00868=0 which isn't logical. I wanted to get what a is, then enter it into either of the equations and get b.