Question

Half angles bby :)

Answer 1

hola

Answer 2

i did #9 and got 1.

Answer 3

#10 is the one im stuck on, after getting 315 on the angle

Answer 4

\[\cos2\Theta=1/2(1+\cos(2\Theta))\]

Answer 5

\(\Huge\color{blue}{ \sf tan( \frac{225}{2})=\sqrt{ \frac{1-cos(225)}{1+cos(225)} } }\)

Answer 6

\(\Huge\color{blue}{ \sf tan( \frac{225}{2})=\sqrt{ \frac{1-cos(225)}{1+cos(225)} } }\)


\(\Huge\color{blue}{ \sf tan( 225)= \frac{sin(225)}{cos(225)}= \frac{sin(180+45)}{cos(180+45)} }\)

tell me what you get for tan 225.

Answer 7

sqroot2 / 2

Answer 8

oh crap

Answer 9

-(sqroot2/2 ) / -sqroot2 /2

Answer 10

i got 1

Answer 11

ok, first tell me what does sin 225 equal to, using

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


AND THEN tell me what does cos 225 equal, using

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

Answer 12

sin a+b = sin 180+45

Answer 13

cos 180 =1
sin 180 = 0
sin 45= cos 45 = √2/2

sin(180+ 45)=sin 180 cos 45 + cos 180 sin 45 =(-1) * √2 / 2 = -√2 / 2
cos(180+45)=cos 180 cos 45 - sin 180 sin 45 = (-1) * √2 / 2 = -√2 / 2

tan (225) = (-√2 / 2) / (-√2 / 2) = 1

Answer 14

yes, it's 1.

Answer 15

lol thanks

Answer 16

yw, still need help with #9 ?

Answer 17

i should be okay. ima start work on 10 now

Answer 18

I got disconnected !

Answer 19

lol its fine

Answer 20

\(\LARGE\color{blue}{ \sf cos(157.5)= \frac{315}{2}= \sqrt{ \frac{1+cos(315)}{2} } }\)

Answer 21

why is there a sqroot over everything if the formula is cos2Θ=1/2(1+cos(2Θ))

Answer 22

nvm i know why

Answer 23

sqroot = 1/2 of whats inside

Answer 24

\(\LARGE\color{blue}{ \sf cos(315)= cos(360-45) }\)

\(\Large\color{blue}{ \sf cos(360-45) =cos(360)cos45-sin(360) sin(45)}\)

sin 360 = 0
cos 360 = 1

\(\Large\color{blue}{ \sf cos(360-45) =1(√2~/~2)-0 (√2~/~2)}\)

\(\Large\color{blue}{ \sf cos(360-45) =√2~/~2}\)

Answer 25

welll its + in the rule but -, but the last part is zero, so doesn't matter.

Answer 26

cosacosb+ (not -) ... EITHER WAY..

Answer 27

whoppsies

Answer 28

you explain so thoroughly trying to find the excact value when i can just glance over at the unit circle and go, "oh look cos315 = sqroot2/2 xD

Answer 29

Thankss