Combining trig equations

[Olmsteadinho]

First of let me say that i am very rusty at math(3 years removed from last math class)... But anyway the question im having trouble with is combining equations and using cosine... The question itself is as follows: combine the equations to obtain an equation involving v alone. Solve this equation to determine the distance from Earth to the sun.. The previous two questions gave me two different equations and i am very lost on how to get v by itself..

v^2+210,200,000^2-2(v)210,200,000cos29.3 = v^2+53,100,000^2-2(v)53,100,000cos31.8

i am very confused as to how to even approach this :/ if someone could allow me the means to solve it myself instead of just giving the answer that would be greatly appreciated..

 

[wjm11]

First of let me say that i am very rusty at math(3 years removed from last math class)... But anyway the question im having trouble with is combining equations and using cosine... The question itself is as follows: combine the equations to obtain an equation involving v alone. Solve this equation to determine the distance from Earth to the sun.. The previous two questions gave me two different equations and i am very lost on how to get v by itself..

v^2+210,200,000^2-2(v)210,200,000cos29.3 = v^2+53,100,000^2-2(v)53,100,000cos31.8

i am very confused as to how to even approach this :/ if someone could allow me the means to solve it myself instead of just giving the answer that would be greatly appreciated..

Collect all the terms on one side of the equation, leaving zero on the other side. You now have a quadratic equation of the form ax^2 + bx + c = 0. Figure out what a, b, and c are in your equation and apply the Quadratic Formula.

 

[Deleted member 4993]

First of let me say that i am very rusty at math(3 years removed from last math class)... But anyway the question im having trouble with is combining equations and using cosine... The question itself is as follows: combine the equations to obtain an equation involving v alone. Solve this equation to determine the distance from Earth to the sun.. The previous two questions gave me two different equations and i am very lost on how to get v by itself..

v^2+210,200,000^2-2(v)210,200,000cos29.3 = v^2+53,100,000^2-2(v)53,100,000cos31.8

i am very confused as to how to even approach this :/ if someone could allow me the means to solve it myself instead of just giving the answer that would be greatly appreciated..

Following the suggestion above, if you collect terms on one side of the "=" sign, you will see that v^2 terms vanish!

You will be left with a linear equation.