How do you draw the right triangle? How do you find the units for the base (x), height (y) and hypotenuse?
I'm using sinθ=y/r, cosθ=x/r, etc.
Please explain!! Thank you so much!
tan theta = y/x = -1
in QII, x < 0, y > 0
x = -1, y = 1
hypotenuse = √(x^2 + y^2) = √(1 + 1) = √2
sinx = y/h = 1/√2 = √2/2
cosx = x/h = -1/√2 = -√2/2
cotx = x/y = -1/1 = -1
secx = h/x = -√2/1
cscx = h/y = √2/1
And here is explanation reply to your comment (tan theta = sqrt3, QIII)
tan theta = sqrt3, tan theta = y/x = √3
y = √3 x
In QIII, x < 0 and y < 0
x = -1, y = -√3, r = √[(-√3)^2 + (-1)^2] = 2
sin theta = y/r = -√3 / 2 = -√3/2
cos theta = x/r = -1/2
cot theta = x/y = -1/(-√3) = √3/3
"How do I draw"
Put one vertex at the origin,
one vertex in the 2nd quadrant along the major diagonal (y = -x),
and the third vertex on the x-axis directly below the 2nd vertex.
We needn't insist on a "unit circle," so just make the vertices
(0,0), (-1,0), and then because tan(theta) = -1, the upper vertex is (-1,1).
Pythagorean Theorem says r = sqrt(1 + 1) = sqrt(2).
Now use the definitions you mentioned in your question.
y = 1, x = - 1 and r = √2
You should be able to find the other five ratios
sin(θ) = 1/√2 = √2/2
cos(θ) = -1/√2 = -√2/2
csc(θ) = √2
sec(θ) = - √2
cot(θ) = - 1
tan θ = 1
Ignore the sign for a moment
In the second quadrant, "sin is positive, cos and tan are negative."
tan θ = -1
tan = opp/adj = 1/1 = 1
opp = 1
adj = 1
hyp = sqrt(1^2 + 1^2) = sqrt(2) (Pythogorean theorem)
sin θ = opp/hyp = 1/√2
cos θ = adj /hyp = -1/√2
tan θ = opp/adj = -1
coθ θ = 1/tan = -1
sec θ = 1/cos = -√2
csc θ = 1/sin = √2
https://gyazo.com/bdb23a8901a7f249cae81ce1e8b5ff04
Sides are 1 , 1 , √2 where √2 is the hypotenuse.
sin ∅ = 1/√2_________csc ∅ = √2
cos ∅ = - 1/√2_______sec ∅ = - √2
tan ∅ = - 1___________cot ∅ = - 1
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Answers & Comments
Verified answer
tan theta = y/x = -1
in QII, x < 0, y > 0
x = -1, y = 1
hypotenuse = √(x^2 + y^2) = √(1 + 1) = √2
sinx = y/h = 1/√2 = √2/2
cosx = x/h = -1/√2 = -√2/2
cotx = x/y = -1/1 = -1
secx = h/x = -√2/1
cscx = h/y = √2/1
And here is explanation reply to your comment (tan theta = sqrt3, QIII)
tan theta = sqrt3, tan theta = y/x = √3
y = √3 x
In QIII, x < 0 and y < 0
x = -1, y = -√3, r = √[(-√3)^2 + (-1)^2] = 2
sin theta = y/r = -√3 / 2 = -√3/2
cos theta = x/r = -1/2
cot theta = x/y = -1/(-√3) = √3/3
"How do I draw"
Put one vertex at the origin,
one vertex in the 2nd quadrant along the major diagonal (y = -x),
and the third vertex on the x-axis directly below the 2nd vertex.
We needn't insist on a "unit circle," so just make the vertices
(0,0), (-1,0), and then because tan(theta) = -1, the upper vertex is (-1,1).
Pythagorean Theorem says r = sqrt(1 + 1) = sqrt(2).
Now use the definitions you mentioned in your question.
y = 1, x = - 1 and r = √2
You should be able to find the other five ratios
sin(θ) = 1/√2 = √2/2
cos(θ) = -1/√2 = -√2/2
csc(θ) = √2
sec(θ) = - √2
cot(θ) = - 1
tan θ = 1
Ignore the sign for a moment
In the second quadrant, "sin is positive, cos and tan are negative."
tan θ = -1
tan = opp/adj = 1/1 = 1
opp = 1
adj = 1
hyp = sqrt(1^2 + 1^2) = sqrt(2) (Pythogorean theorem)
sin θ = opp/hyp = 1/√2
cos θ = adj /hyp = -1/√2
tan θ = opp/adj = -1
coθ θ = 1/tan = -1
sec θ = 1/cos = -√2
csc θ = 1/sin = √2
https://gyazo.com/bdb23a8901a7f249cae81ce1e8b5ff04
Sides are 1 , 1 , √2 where √2 is the hypotenuse.
sin ∅ = 1/√2_________csc ∅ = √2
cos ∅ = - 1/√2_______sec ∅ = - √2
tan ∅ = - 1___________cot ∅ = - 1