Name: ___________________

Date:___________________

kwizNET Subscribers, please login to turn off the Ads!
Email us to get an instant 20% discount on highly effective K-12 Math & English kwizNET Programs!

High School Mathematics - 2
Signs of Trigonometric Functions for Negative Angles

θsin θ cos θtan θ cosec θ sec θ cot θ
0010n.d.1n.d.
301/23/21/322/33
451/21/21221
603/21/232/321/3
9010n.d.1n.d.0
Signs of trigonometric functions for negative angles
Let P(x,y) be a point on the unit circle with centre at origin such that angle AOP = θ. If angle AOQ = -θ, then the co-ordinates of the point Q will be (x,-y). Hence
cos(-θ) = x = cosθ
sin(-θ) = -y = -sinθ
III IIIIV
sinθ ++--
cosθ +--+
tanθ +-+-
cosecθ ++--
secθ +--+
cotθ +-+-
In the first quadrant, as θ increases from 0 to π/2, sinθ increases from 0 to 1.
In the second quadrant, as θ increases from to π/2 to π,to π sinθ decreases from 1 to 0.
In the third quadrant, as θ increases from π to 3π/2, sinθ decreases from 0 to -1.
In the fourth quadrant, sinθ increases from -1 to 0, as θ increases from 3π/2 to 2π.


Directions: Solve the following.

Name: ___________________

Date:___________________

High School Mathematics - 2
Signs of Trigonometric Functions for Negative Angles