Jana is proving that the following trigonometric identity is true: cos(−θ)⋅tanθ=sinθ Which step would be the first line of her proof? cosθ⋅tanθ=sinθ cos(−θ)⋅tan(−θ)=sinθ cos(−θ)⋅tanθ=sin(−θ) cosθ⋅tan(−θ)=sinθ

Step-by-step explanation:

The given trigonometric identity is .

Jana has to recall that, the cosine function is an even function.

For that matter, .

Jana has to apply this property by substituting  for  in the given identity to obtain,

.

Note that, the sine and the tangent functions are odd functions

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so:

congruent segments

step-by-step explanation: