cosx = 4/5 and x is in quad IV
So sinx = - 3/5
sin 2x = 2sinxcosx
= 2(-3/5)(4/5) = -24/25
if tan x = -7/24 and 3π/2 < x <2π find cot x/2
Thanks so much!
Don't post a new question in the thread of a question.
Tutors will see a reply and ignore it
Start a new entry.
if tanx = -7/24 and x is in IV
then sin x = -7/25 and cosx = 24/25
= cos x/2 / sin x/2
recall cos 2A = 2cos^2 A - 1 or 1 - 2sin^2 A
cos x = 2cos^ x/2 - 1
24/25 + 1 = 2cos^2 x/2 = 49/25
cos^2 x/2 = 49/50
cos x/2 = -7/(5√2) , if x is in IV , then x/2 is in II , therefore negative
cos x = 1 - 2sin^2 x/2
24/25 - 1 = -2sin^2 x/2 = -1/25
sin^2 x/2 = 1/50
sin x/2 = +1/(5√2)
cot x/2 = cos x/2 / sin x/2
= -7/(5√2) / 1/(5√2) = -7
Thank you soo much!
Trigonometry - use the appropriate trig identity (sum and difference, half angle...
MATH - 1.)Find the exact solution algebriacally, if possible: (PLEASE SHOW ALL ...
trig - A coil of wire rotating in a magnetic field induces a coltage E=20sin((...
trig - use a half-angle identity to find the exact value of tan 105 degrees.
math - find the exact value using a double-angle identity
trip - for sin2x+cosx=0, use double-angle or half-angle formula to simplify the ...
Trig - find cos x/2, sin x = 1/4, 360 < x < 450, use half-angle identity
trig - Use the double angle formula to verify the identity cotxsin2x=1+cos2x
Trig - Use a half-angle identity to find the exact value for sec(x/2) if sinx...
ah trig help - use an apropriate sum or difference indentity to prove the double...