Difference between revisions of "2006 iTest Problems/Problem 9"
Rockmanex3 (talk | contribs) (Solution to Problem 9 -- Sines and Cosines) |
Rockmanex3 (talk | contribs) m |
||
Line 18: | Line 18: | ||
==See Also== | ==See Also== | ||
− | {{iTest box|year=2006| | + | {{iTest box|year=2006|num-b=8|num-a=10|ver=[[2006 iTest Problems/Problem U1|U1]] '''•''' [[2006 iTest Problems/Problem U2|U2]] '''•''' [[2006 iTest Problems/Problem U3|U3]] '''•''' [[2006 iTest Problems/Problem U4|U4]] '''•''' [[2006 iTest Problems/Problem U5|U5]] '''•''' [[2006 iTest Problems/Problem U6|U6]] '''•''' [[2006 iTest Problems/Problem U7|U7]] '''•''' [[2006 iTest Problems/Problem U8|U8]] '''•''' [[2006 iTest Problems/Problem U9|U9]] '''•''' [[2006 iTest Problems/Problem U10|U10]]}} |
[[Category:Introductory Trigonometry Problems]] | [[Category:Introductory Trigonometry Problems]] |
Revision as of 20:56, 28 November 2018
Problem
If and is in the third quadrant, what is the absolute value of ?
Solution
Since is in the third quadrant, is negative, so . Using the half-angle identity (or the double angle cosine identity), The answer is .
See Also
2006 iTest (Problems) | ||
Preceded by: Problem 8 |
Followed by: Problem 10 | |
1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 • 16 • 17 • 18 • 19 • 20 • 21 • 22 • 23 • 24 • 25 • 26 • 27 • 28 • 29 • 30 • 31 • 32 • 33 • 34 • 35 • 36 • 37 • 38 • 39 • 40 • U1 • U2 • U3 • U4 • U5 • U6 • U7 • U8 • U9 • U10 |