Question

CAN ANYONE HELP ME UNDERSTAND THIS?!:(
Given the following values: sinA=65/97, sinB=20/29, cosA=72/97, cosB=21/29.
Find sin〖(A+B)〗
Find sin〖(A-B)〗
Find cos〖(A+B)〗
Find cos〖(A-B)〗

Answer 1

sin(A+B)=sin(A)cos(B)+sin(B)cos(A)

Answer 2

just enter in your given values like so:
\[\sin(A+B)=\frac{65}{97} \cdot \frac{21}{29} +\frac{20}{29} \cdot \frac{72}{97}\]

Answer 3

@hannaolsonnn do you understand
do you think you can simplify that?
and so find the other things there

Answer 4

yes!! thank you so much for helping!! i am going to try and find the answer, may I tag you for reassurance once I find it? (:

Answer 5

sure

Answer 6

okay I think I did this wrong.. Please don't think I am so stupid or something we just started this is class and I do not understand it at all. SO when I enter this in my calculator I would enter sin(65/97*21/29+20/29*72/97) ?? That is probably wrong.. I really have no idea how to do this at all. All we have been taught so far is how to enter simple equations into the calculator dealing with triangles and stuff. I really need help.

Answer 7

why is there a sin there at all?

Answer 8

\[\sin(A+B)=\frac{65}{97} \cdot \frac{21}{29} +\frac{20}{29} \cdot \frac{72}{97} \\ =\frac{65 \cdot 21 +20 \cdot 72}{97 \cdot 29}\]
all i did was combined the fractions since they had a common denominator

Answer 9

now you need to perform order or operations on top and bottom

Answer 10

\[=\frac{1365+1440}{2813}=\frac{2805}{2813} \text{ then you reduce the fraction if you can }\]

Answer 11

OMG THANK YOU SO MUCH i really need the help ps i am new here so could you tell me how i could give you a medal?
SO for sin (a-b) would you combine the fractions again? or what would you do before you perform order of operations??

Answer 12

well you know sin(a-b)=sin(a)cos(b)-cos(a)sin(b) right?

Answer 13

just plug in as I did before
and apply the order of operations again

Answer 14

sin ( a-b) = 65/97 times 21/29 - 72/90 times 20/29
is that correct so far?

Answer 15

@freckles when I do the order of operations I get this