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anonymous
 one year ago
Find the exact value of each expression:
a. sin20degcos80decos20degsin80deg
b. cos 5pi/12cos7pi/12sin5pi/12sin7pi/12
anonymous
 one year ago
Find the exact value of each expression: a. sin20degcos80decos20degsin80deg b. cos 5pi/12cos7pi/12sin5pi/12sin7pi/12

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anonymous
 one year ago
Best ResponseYou've already chosen the best response.0@jim_thompson5910 does that make sense or should i write out again?

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.2you don't need to write "deg"

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.2hint: see page 2 of http://tutorial.math.lamar.edu/pdf/Trig_Cheat_Sheet.pdf specifically the "Sum and Difference Formulas" section

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0so it would be the formula stating that sin(a +orb)=sinacosbcosasinb?

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.2you'll use the cosine version for part b

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0oh okay so for the test tomorrow I should just memorize those formulas? but so now to solve it, it would be (20+80) or (2080)? so the answer is 100 or 60?

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.2sin(20)cos(80)cos(20)sin(80) = sin(2080) = sin(60) = ???

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0would it be sin(60)?

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.2sin(60) is not equal to sin(60)

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0oh .. i thought you put the question marks as in that it was wrong

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.2no it's my way of putting a blank

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.2so you'd fill in the blank

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.2sin(60) = sin(60) = _______________

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.2you're thinking of 60 degrees = pi/3 radians

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.2use the unit circle and determine sin(60)

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0okay i've been looking at the unit circle for 5 minutes and because you're determining sin60 you would be looking in the 3 and fourth quadrants right?

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0and looking for a distance of 60 degrees the opposite way? I'm just trying to remember what my teacher said.. He said something like that @jim_thompson5910

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.2dw:1433398564125:dw

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.2dw:1433398585790:dw

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.2dw:1433398602906:dw

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.2determine the y coordinate of that point, then make it negative that will be the value of sin(60)

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.2\[\Large \sin(60) = \frac{\sqrt{3}}{2}\] \[\Large \sin(60) = \frac{\sqrt{3}}{2}\]

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0okay so I just look for it on the unit circle and determine it through the coordinate?

jim_thompson5910
 one year ago
Best ResponseYou've already chosen the best response.2yes, x = cos(theta) and y = sin(theta)

anonymous
 one year ago
Best ResponseYou've already chosen the best response.0now for part b do you find pi/6 on the unit circle and look at x coordinate to determine the value?
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