Question 720779
<pre>
Remember the sentence "ALL STUDENTS TAKE CALCULUS" to remember the
letters A,S,T,C for these words: 

1. the word ALL
2. the word SINE
3. the word TANGENT
4. the word COSINE

This works for the basic three trig functions SINE, COSINE, TANGENT.

Quadrant I:   A for ALL three of the basic three trig functions are positive
              in quadrant I which is 0 < <font face="symbol">q</font> < 90° if <font face="symbol">q</font> is measured in degrees 
              or 0 < <font face="symbol">q</font> < {{{pi/2}}} if <font face="symbol">q</font> is measured in radians.


Quadrant II:  S for the SINE is positive and the other two basic trig functions
              are negative in quadrant II which is 90° < <font face="symbol">q</font> < 180° if <font face="symbol">q</font> is 
              measured in degrees or{{{pi/2}}} < <font face="symbol">q</font> < <font face="symbol">p</font> if <font face="symbol">q</font> is measured in radians.

Quadrant III: T for the TANGENT is positive and the other two basic trig functions
              are negative in quadrant III which is 180° < <font face="symbol">q</font> < 270° if <font face="symbol">q</font> is 
              measured in degrees or <font face="symbol">p</font> < <font face="symbol">q</font> < {{{3pi/2}}} if <font face="symbol">q</font> is measured in radians.

Quadrant IV:  C for the COSINE is positive and the other two basic trig functions
              are negative in quadrant IV which is 270° < <font face="symbol">q</font> < 360° if <font face="symbol">q</font> is 
              measured in degrees or{{{3pi/2}}} < <font face="symbol">q</font> < 2<font face="symbol">p</font> if <font face="symbol">q</font> is measured in radians.

The above scheme tells you what signs the three basic trig functions SINE,
COSINE, and TANGENT have in the various quadrants.  It does not work for
SECANT, COSECANT and COTANGENT, so don't mistake the S and C from "ALL
STUDENTS TAKE CALCULUS" for those, but only for SINR and COSINE.  The way to
remember the signs of the SECANT, COSECANT, and COTANGENT, is to remember that
the SECANT is the reciprocal of the COSINE and the SECANT will have the same
sign as the COSINE. The same for the other two reciprocal functions.  The
COSECANT is the reciprocal of the SINE and the COSECANT will have the same
sign as the SINE. The COTANGENT is the reciprocal of the TANGENT and the
COTANGENT will have the same sign as the TANGENT.

Your question is:
</pre>
if sin<font face="symbol">q</font> is negative and cos<font face="symbol">q</font> is negative in which quadrant does the terminal side <font face="symbol">q</font> lie?
<pre>

Think of the sentence "ALL STUDENTS TAKE CALCULUS".  The SINE is positive
in quadrants I and II and negative in quadrants III and IV.  So the answer
is either quadrant III or IV.  The cosine is positive in quadrants I and IV,
and negative in quadrants II and III, so that eliminates quadrant IV, and so
the answer is quadrant III.

Edwin</pre>