If cot θ = -√3 then how do you find the exact value of theta in QII without using the calculator
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If cot θ = -√3 then how do you find the exact value of theta in QII without using the calculator

[From: ] [author: ] [Date: 11-10-20] [Hit: ]
since the short side is opposite the 30 degree angle,you need to know your special angles! (multiples of 30,45, and 60)-first of all there is no minus value for cot theta.in your case adj side = 1.......
find cot θ" = √3 first

cot θ" = √3
tan θ" = 1/√3

this is an exact triangle, with sides 1 and √3 and hypotenuse of 2
recall the angle required for this triangle

θ" = 30 degrees

but tan θ negative
on the unit circle, tan θ is negative in the 2nd and 4th quadrants which correspond to θ = 180 - θ" and θ = 360 - θ" respectively

θ = 180 - 30
= 150 degrees
θ = 360 - 30
= 330 degrees

these are the two solutions

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cot = x / y
in Q2, x is negative and y is positve, so
x = -sqrt(3) and y = 1

we also know that x^2 + y^2 = r^2
(-sqrt(3))^2 + 1^2 = 3 + 1 = 4 = r^2
r = 2 (always positive)

this defines a 30-60-90 triangle, since the ratio of the sides is 1:sqrt(3):2
since the short side is opposite the 30 degree angle, that means it makes the 30 degree angle with the x-axis

180 - 30 = 150

theta = 150 or 5pi/6

you need to know your special angles! (multiples of 30,45, and 60)

-
first of all there is no minus value for cot theta.
cot theta is equal to adjacent side over opposite side
in your case adj side = 1.7321 & opp side = 1
therefore angle is 30 deg
(it should be plus & not minus)

-
You have a 1, 2, sqrt(3) triangle in Q2
θ = 180 - 30 = 150 degrees

-
Don't you just hate Calc lol
1
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