any smart math people here?

[habeansha]

well maybe you dont have to be that smart but i have some problems doing trig
the first one is: Show that cos(x/2) sin(3x/2) = (sinx + sin2x)
i know that you are supposed to substitute all those trig function things in it but i kind of forgot how to
the only that i can see substituting in is the double angle one for sin2x
could anyone walk me through the process maybe?

the second one is this
<a href="http://photobucket.com" target="_blank"><img src="http://img.photobucket.com/albums/v343/habeansha/problem1.jpg" border="0" alt="Photo Sharing and Video Hosting at Photobucket"></a>
that one i just have no idea
i can get the one side of the top triangle with the pythagorean thm but thats all i can think of to do
any help would be appreciated

 

[Familia323]

wow... I used to know this..... If I could figure out just one more angle or side I could help you, but I just can't remember how to start..

 

[RallyeRedSi]

well maybe you dont have to be that smart but i have some problems doing trig
the first one is: Show that cos(x/2) sin(3x/2) = (sinx + sin2x)
i know that you are supposed to substitute all those trig function things in it but i kind of forgot how to
the only that i can see substituting in is the double angle one for sin2x
could anyone walk me through the process maybe?

the second one is this
<a href="http://photobucket.com" target="_blank"><img src="http://img.photobucket.com/albums/v343/habeansha/problem1.jpg" border="0" alt="Photo Sharing and Video Hosting at Photobucket"></a>
that one i just have no idea
i can get the one side of the top triangle with the pythagorean thm but thats all i can think of to do
any help would be appreciated

wow 7 years ago i could of done this for you no problem now (sad2)

 

[geomatics_tech]

sine law for number 2

 

[ChopstickHero]

SOH CAH TOA!

this was so gr 9.

 

[wmbeaver]

for the first one, this is all i got to, i don't know if it will help or not though ( i wasn't very good at this stuff):

as you can see, i got almost the whole equation over 2, and for the part that isnt, just multiply the top part of the fraction by 2, and put it over 2. everytime i do these, i just always end up going in circles and can never find that one step that gets you the answer

for the second:
i believe x is equal to segment BC, i forgot why, but just draw it to scale on paper, and you'll see, i'll post up some more info in just a little bit if i can figure it out

this might help:
http://www.sosmath.com/trig/Trig5/trig5/trig5.html

good luck

 

[mhrebin]

man. 12th grade. im out of practice.lol

sooorrryyyy. ( this used to be my thing too, until i became a graphic designer.lol)

 

[daonly1around]

yea, about 9 years ago id could do both of theese in about 5 mins or less.... ahhh the memories....

 

[habeansha]

thanks for everyones help i think i got it now