What is cosΘ if tanΘ = 6/17?

2 Answers
Apr 1, 2018

=> (17sqrt(13) ) / 65

Explanation:

We know tantheta = "opposite"/"adjacent"

Hence opposite" = 6 and "adjacent" = 17

Hence using Pythagorus rule: a^2 + b^2 = c^2

=> 6^2 + 17^2 = c^2 => c = 5sqrt(13)

=> "hypotenuse" = 5sqrt(13)

We know costheta = "adjacent" / "hypotenuse"

=> cos theta = 17/(5sqrt(13 ) )

=> (17sqrt(13) ) / 65

Apr 1, 2018

color(blue)((17sqrt(13))/65)

Explanation:

enter image source here

From diagram, we have:

tan(theta)="opposite"/"adjacent"=6/17

cos(theta)="adjacent"/"hypotenuse"=17/c

We need to find bbc:

Using Pythagoras' Theorem:

c^2=6^2+17^2

c=sqrt((6)^2+(17)^2)=sqrt(325)=5sqrt(13)

cos(theta)="adjacent"/"hypotenuse"=17/(5sqrt(13))=color(blue)((17sqrt(13))/65)