Question

Solve the equation on the interval [0, 2π).

cos x + 2 cos x sin x = 0

Answer 1

@Calcmathlete

Answer 2

factor the left side
cos x (1 + 2 sin x ) = 0

Answer 3

so its A?

Answer 4

so do you know what angles have a cos of 0?
angles between o and 2pi?

Answer 5

x = pi/2 has a cos of 0

Answer 6

so is it A?

Answer 7

hmmm - you are twisting my arm - 3pi/2 also has a cos of 0
what about the sine bit?
2 sin x = -1
so sin x = -1/2

what angles have a sine of -1/2?
clue: sin pi/6 has a sine of 1/2

Answer 8

if you are unhappy with radians pi/6 = 30 degrees and sine is negative in 3rd and 4th quadrants

Answer 9

7pi/6 and 11pi/6 so its B!

Answer 10

right

Answer 11

thnx! srry for twisting ur arm :)

Answer 12

lol
- i twisted yours in reply

Answer 13

yw

Answer 14

i have one more! LAST one i promise :)

Solve the equation on the interval [0, 2π).

sec(x/2) = cos(x/2)

Im not sure how to simplify or factor

Answer 15

@cwrw238

Answer 16

change sec(x/2) to 1 / cos (x/2)
giving 1 / cos(x/2) = cos(x/2)

Answer 17

ok. then what do i do?

Answer 18

so cos (x/2) = ?

Answer 19

1/x = x
so what is x?

Answer 20

2 cos (x/2) ?

Answer 21

nope

Answer 22

cos(x/2)^2?