SOLUTION: Please help me find Cos(A-b) in the following equation. Equation: https://s28.postimg.org/fbpu1fv25/tan_a_5.png Thank you.

Algebra ->  Test -> SOLUTION: Please help me find Cos(A-b) in the following equation. Equation: https://s28.postimg.org/fbpu1fv25/tan_a_5.png Thank you.      Log On


   

Question 1064902: Please help me find Cos(A-b) in the following equation.
Equation: https://s28.postimg.org/fbpu1fv25/tan_a_5.png
Thank you.
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
tan%28A%29=5=5%2F1=sin%28A%29%2Fcos%28A%29
so,
sin%28A%29=-5%2Fsqrt%285%5E2%2B1%5E2%29=-5%2Fsqrt%2826%29=-%285%2F26%29sqrt%2826%29
cos%28A%29=-1%2Fsqrt%2826%29=-sqrt%2826%29%2F26
and
sin%28B%29=2%2F3
cos%28B%29=-sqrt%281-%282%2F3%29%5E2%29=-sqrt%281-4%2F9%29=-sqrt%285%2F9%29=-sqrt%285%29%2F3
.
.
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Now use the formula,
cos%28A-B%29=cos%28A%29cos%28B%29%2Bsin%28A%29sin%28B%29