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# sorry but another question

+1
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4

sorry if this seems like too many questions in the same day but today is math day for me so ive been working on this stuff all day haha ;-;

here's this other piece of pain that i'm struggling with:

Consider the following points on the graphs of $y = \sin(x)$ and $y = \sin(2x)$, with the added vertical dashed lines: What are c and d in that order?

thank you so so so much for your help in advance!!! (you all are so great at math and it's so much more helpful than anything else ive tried)

:) <3

i swear this is the last question lol i dont wanna seem ungrateful for you guys' help haha

Sep 6, 2023
edited by heartSTORM907  Sep 6, 2023

#1
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The point  (a, -4/5)  is  on the  graph of sin x

So

a  is a third quadrant angle  so sin a =  -4/5   and   cos a =  -3/5

And   (a, c)  is on the graph of  sin (2x)

So

sin (2a)  =  2sin a  cos a  =     2 (-4/5) (-3/5)  = 2 (12/25) = 24/25  = c

Likewise

(b , 5/13)  is on sin x

sin b = 5/13

b is a first quadrant angle so cos b =  12/13

So

sin (2b)  = 2 sin b  cos b  =   2 (5/13) (12/13)  =  120 / 169  =  d   Sep 6, 2023
edited by CPhill  Sep 6, 2023
edited by CPhill  Sep 6, 2023
#2
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omg thank you so much for your help!!!!! :D

Sep 6, 2023
#3
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heartSTORM907, you bloody idiot! You have asked many questions already, including ones about quadratics. It seems that you struggle to understand them. If you read and understood the solutions, you should be able to handle simpler tasks like this. However, you simply copy and paste the answer without caring about the time and effort wasted. These homework helpers may be egotistical, but they are competent mathematicians who could teach basic math.

GA

Guest Sep 8, 2023
edited by Guest  Sep 8, 2023
#4
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For the record: Post #3, signed by GA, is not by the real GA.

GA

--. .-

GingerAle  Sep 9, 2023
edited by GingerAle  Sep 9, 2023
edited by GingerAle  Sep 9, 2023