**Problem : **
Why do the following pairs of functions always have the same sign: sine
and cosecant, cosine and secant, tangent and cotangent?

**Problem : **
In which quadrant do the most trigonometric
functions have negative signs?

**Problem : **
Which value in the following group is not equal to the others:
sin()
,
cos(*Π*)
,
cot()
,
sec(0)
?

**Problem : **
Which value in the following group has a different sign from the others:
sin()
,
sec()
,
cot()
,
cos()
?

**Problem : **
When
*θ* = *Π*
, which two trigonometric functions are undefined?