Which of the following is an identity?

Step-by-step explanation:

It can be useful to write each of these in terms of sine and cosine. Of course the relationship between sine and cosine is ...

  sin²x + cos²x = 1 . . . . . eliminates choice B

A: (1/sin +cos/sin)² = ((1+cos)/sin)² ≠ 1

C: 1/sin² +(cos/sin)² = (1+cos²)/sin² ≠ 1

D: sin²(1/cos²) +1 = (sin²+cos²)/cos² = 1/cos² . . . (left side)

  (sin/cos)²(1/sin²) = 1/cos² . . . (right side)

left side = right side, so this is an identity

75 tickets have been sold so far.

step-by-step explanation:

in this question it is clearly mentioned that 45 children's tickets have been sold and this number is 60% of the total tickets sold.

now let's assume the total number of tickets sold be x.

then 60% of x = 45

⇒

⇒ x(.6) = 45

by dividing with .6 on both the sides of the equation

⇒ x = 75

therefore 75 tickets have been sold so far.

set each factor equal to 0

4x-3 = 0

2x-1 = 0

solve for x.

4x-3=0

4x=3

x= 3/4

solve for x. 

2x-1= 0

2x= 1

x= 1/2

eventually after a few more steps, your answer should be 1/2 is less than or equal to x and 3/4 is greater than or equal to x