Make a sketch in your notes regarding CAST
It tells you in which quadrants the main trig ratios of (S)ine, (C)osine and (T)angent are positive.
Of course if the cosine is positive then its reciprocal, the secant, is also positive, etc
since tanØ = 5/7 = y/x
x = -7 , y = -5 , since we are in quadrant III
r^2 = 7^2 + 5^2
r = √74
cosØ = x/r = -7/√74
secØ = -√74/7
The CAST rule makes all this +/- stuff really easy.
Suppose tan(theta)=5/7 and theta belongs to Quadrant III, find the exact value of sec(theta)?
I already took the steps to solve this problem but I am confused if whether or not sec(theta)is positive or negative sqrt(74)/7
Any help is greatly appreciated!
2 answers
Got it, thanks for the help!
2 answers