Sunday
April 20, 2014

Homework Help: pre-calc

Posted by sarah on Saturday, May 5, 2007 at 4:10pm.

Can someone help me find the exact value of 4csc(3pi/4)-cot(-pi/4)?
Thanks!

cotx =1/tanx
cscx = 1/sinx

If you find it easier to conceptualize in degrees, realize that pi/4 radians is 45 and 3pi/4 is then 135

If you know the CAST rule, it is easy to see that -pi/4 is in the fourth quadrant and tan(-pi/4) or tan(-45) = -1
therefore cot(-pi/4) = -1

3pi/4 or 135 is in the second quadrant where the sine is positive.
so sin(3pi/4) = 1/(√2)
then csc(3pi/4) = √2
and 4csc(3pi/4) = 4√2

so the exact value of 3csc(3pi/4) - cot(-pi/4)
= 4√2 + 1

Answer this Question

First Name:
School Subject:
Answer:

Related Questions

Pre-Calculus - Find a numerical value of one trigonometric function of x if tanx...
drwls - My previous question: Verify that (secx/sinx)*(cotx/cscx)=cscx is an ...
Trig - How do I find all solutions in the interval [0, 2Pi): cotx=cscx-1 the ...
trig - express this in sinx (1/ cscx + cotx )+ (1/cscx- cotx) i got 2sinx is ...
trigonometry - How do you find: cot(-5pie/4)? you have to know that cotx = 1/...
Pr-Cal/Trig - 1)if the graph of f(x)=cotx is transformed by a horizontal shrink ...
calculus - express in sinx 1 1 ---------- + -------- cscx + cotx cscx - cotx and...
Pre-Calc - I posted yesterday and didn't get a response so I'm hoping someone ...
CALC HW - FIND THE X VALUES OF ALL POINTS, -2PI LESS THAN OR EQUAL TO X LESS ...
Pre-Calc/Math - If cosx= -2/3 and pi/2, find the exact value of cos(pi/3-x)

Search
Members