Question

verify the identity and show all work 1- tanxtany= cos(x+y)/cosxcosy

Answer 1

write tan in terms of sin and cos

Answer 2

so 1-(sinx/cosx)sin x/sin y

Answer 3

tan y = ?

Answer 4

siny/cosy

Answer 5

so it would be
\(\huge 1-\frac{sin x}{cosx}\times \frac{sin y}{cos y}\)
right ?
now cross-multiply.

Answer 6

1-sinxcosy sinycosx

Answer 7

it would be
\(\huge \frac{cos x cos y -sin x sin y}{cos x cos y}\)
got this ?

Answer 8

ok yea

Answer 9

now numerator is the standard formula for cos (x+y)

Answer 10

ohh ok got it !(: