S spoog74 Full Member 10+ Year Member Joined Jan 31, 2011 Messages 423 Reaction score 0 Jun 2, 2011 #1 Anyone know of any good tricks to solve sin 8pi/7 ? The answer is something like -sinpi/7 But how would u know that? Members don't see this ad.
Anyone know of any good tricks to solve sin 8pi/7 ? The answer is something like -sinpi/7 But how would u know that? Members don't see this ad.
PhansterZ Full Member Verified Member Physician Dentist Verified Expert 15+ Year Member Joined Jun 18, 2006 Messages 364 Reaction score 594 Jun 2, 2011 #2 spoog74 said: Anyone know of any good tricks to solve sin 8pi/7 ? The answer is something like -sinpi/7 But how would u know that? Click to expand... 8 pi/7 is in the third quadrant, which means sin is negative. to get how far it goes into the third quadrant, just take away pi. 8pi/7 - pi = 8pi/7 - 7pi/7 = pi/7 it goes pi/7 into the third quadrant, in which sin is negative. therefore it's -sin pi/7 Upvote 0 Downvote
spoog74 said: Anyone know of any good tricks to solve sin 8pi/7 ? The answer is something like -sinpi/7 But how would u know that? Click to expand... 8 pi/7 is in the third quadrant, which means sin is negative. to get how far it goes into the third quadrant, just take away pi. 8pi/7 - pi = 8pi/7 - 7pi/7 = pi/7 it goes pi/7 into the third quadrant, in which sin is negative. therefore it's -sin pi/7
S spoog74 Full Member 10+ Year Member Joined Jan 31, 2011 Messages 423 Reaction score 0 Jun 2, 2011 #3 PhansterZ said: 8 pi/7 is in the third quadrant, which means sin is negative. to get how far it goes into the third quadrant, just take away pi. 8pi/7 - pi = 8pi/7 - 7pi/7 = pi/7 it goes pi/7 into the third quadrant, in which sin is negative. therefore it's -sin pi/7 Click to expand... this is probably a dumb question, but how do you know it is in the third quadrant? Are there facts i should memorize pertaining to this question? Upvote 0 Downvote
PhansterZ said: 8 pi/7 is in the third quadrant, which means sin is negative. to get how far it goes into the third quadrant, just take away pi. 8pi/7 - pi = 8pi/7 - 7pi/7 = pi/7 it goes pi/7 into the third quadrant, in which sin is negative. therefore it's -sin pi/7 Click to expand... this is probably a dumb question, but how do you know it is in the third quadrant? Are there facts i should memorize pertaining to this question?
F FROGGBUSTER Full Member 10+ Year Member Joined Jul 22, 2010 Messages 961 Reaction score 4 Jun 2, 2011 #4 Memorize and know how to apply the unit circle, it will save you time on the DAT. 👍 Upvote 0 Downvote
PhansterZ Full Member Verified Member Physician Dentist Verified Expert 15+ Year Member Joined Jun 18, 2006 Messages 364 Reaction score 594 Jun 2, 2011 #5 spoog74 said: this is probably a dumb question, but how do you know it is in the third quadrant? Are there facts i should memorize pertaining to this question? Click to expand... if it helps you can convert the radians into degrees. pi = 180 degrees. so 8pi/7 ~ 206 degrees. and 206 degrees is in third quadrant. Well, you should know where the angle lies, so you can find out if the values or sin and cos are positive or negative. In other words, you should be familiar with the unit circle. Upvote 0 Downvote
spoog74 said: this is probably a dumb question, but how do you know it is in the third quadrant? Are there facts i should memorize pertaining to this question? Click to expand... if it helps you can convert the radians into degrees. pi = 180 degrees. so 8pi/7 ~ 206 degrees. and 206 degrees is in third quadrant. Well, you should know where the angle lies, so you can find out if the values or sin and cos are positive or negative. In other words, you should be familiar with the unit circle.
S spoog74 Full Member 10+ Year Member Joined Jan 31, 2011 Messages 423 Reaction score 0 Jun 2, 2011 #6 PhansterZ said: if it helps you can convert the radians into degrees. pi = 180 degrees. so 8pi/7 ~ 206 degrees. and 206 degrees is in third quadrant. Well, you should know where the angle lies, so you can find out if the values or sin and cos are positive or negative. In other words, you should be familiar with the unit circle. Click to expand... Thank u aLL!! Upvote 0 Downvote
PhansterZ said: if it helps you can convert the radians into degrees. pi = 180 degrees. so 8pi/7 ~ 206 degrees. and 206 degrees is in third quadrant. Well, you should know where the angle lies, so you can find out if the values or sin and cos are positive or negative. In other words, you should be familiar with the unit circle. Click to expand... Thank u aLL!!