I am not doing this trig right
given tan(A+B) =4; tanB=3/5
using formula (tanA + tanB)/(1-tanA*tanB)
so replacing tanB with 3/5
(tanA +3/5)/(1-tanA*3/5)=4
I am at a total block can you help please?

Question

I am not doing this trig right
given tan(A+B) =4; tanB=3/5
using formula (tanA + tanB)/(1-tanA*tanB)
so replacing tanB with 3/5
(tanA +3/5)/(1-tanA*3/5)=4
I am at a total block can you help please?

amistre64 · Answer

the rest is basic algebra ... multiply, distribute, collect like terms ... factor, etc

amistre64 · Answer

(x+3)/(1-3x) = 4

how do you solve for x?

anonymous · Answer

sorry my computer locked up

anonymous · Answer

I got  tanA+3/5=4(1-tanA*(3/5))
tanA+3/5=4-4*tanA*(3/5)
tanA+4tanA*3/5=4-(3/5)
tanA+(12tanA/5)=17/5
(5tanA/5)+(12tanA/5)=17/5
17tanA/5=17/5
tanA=1 
Thanks for the push!