How would i solve
Cosx (cosx + 1) = 0 0 < x < 360
idk if that's the exact question but I had it earlier and could not figure it out
#Trig
weary prism
polar ocean
How would i solve
Cosx (cosx + 1) = 0 0 < x < 360
idk if that's the exact...
It’s in a factorised form so you can equate each bracket to 0
weary prism
It’s in a factorised form so you can equate each bracket to 0
the solutions i believe were something like x = 180, 270 and one more, how would i end up with that if i equated them to 0?
polar ocean
the solutions i believe were something like x = 180, 270 and one more, how would...
When is cosx 0
weary prism
When is cosx 0
ik but like how would u evaluate it out?
distant basin
ik but like how would u evaluate it out?
cosx=0
x=cos^-1(0)
then use facts about cos to work out subsequent solutions in the given range
weary prism
yeah i looked a little online and found out, but im still not sure how 270 is a solution, unless the answer book thing is wrong
weary prism
cosx=0
x=cos^-1(0)
but ty
distant basin
yeah i looked a little online and found out, but im still not sure how 270 is a ...
360-90
=270
or just look at cos
and when your y=0
it crosses twice
weary prism
oh right, wait, would 0 be considered a positive then when looking at the cast diagram?
x = 90, 270, 360?
distant basin
oh right, wait, would 0 be considered a positive then when looking at the cast d...
positive tho
weary prism
it's not worth the effort
how come, its decently fast no?
at least the way my teacher taught it
weary prism
positive tho
ahh ok ty
distant basin
how come, its decently fast no?
just try using a graph
it ends up being easier
and there's just rules you can learn
weary prism
ehh, cast isnt too hard for me ig
distant basin
to skip using cast entirely
like I know tan will always repeat 180
sin is 180-theta
Cos is 360-theta
distant basin
I can do it
weary prism
u think u could help me with one, its a proof but with a triangle that isnt 90 degrees
distant basin
I can try lmao
weary prism
alr, one sec lemme get it
distant basin
whether I can do it tho different story
weary prism
its not the best pic cus its on a textbook but its 3(b)
unless im stupid, no clue how to do it
oh wait, this is double angles not compound, my bad
polar ocean
Whats β in terms of α
weary prism
Whats β in terms of α
i can say i have absolutely no clue
yoo i got close kinda, cos2alpha = 7/25
@thick skiff
polar ocean
3a?
weary prism
no, 3b
thick skiff
cant you work out a from part a
thick skiff
its non calc
??
polar ocean
Well cos(90-a) is 6/10
weary prism
cant you work out a from part a
dont think so but i have really no clue
polar ocean
So square it double it minus 1
weary prism
So square it double it minus 1
aint that for 2x? or 2a
polar ocean
Cos(2A)=2cos(A)^2 - 1 where A = 90-A
cos(180-2α) = -cos(2α)
sin(2α) = 24/25 so cos(2α) = 7/25
So cos(β) = -7/25
weary prism
am i dmb or something, did not know that cos(180-2a) = -cos2a
polar ocean
You can look at the unit circle