Multiply out the quadratic equation to get cosΘ² – 2cosΘsinΘ + sinΘ²  

Then use the following trig identities to simplify the expression:

sin2Θ = 2sinΘcosΘ

sinΘ² + cosΘ² = 1 

1 – sin2Θ is the correct answer for (cosΘ – sinΘ)²  

1 + sin2Θ is the correct answer for (cosΘ + sinΘ)² 

The range of a cosine wave is altered by the coefficient placed in front of the base equation. So, if you have , this means that the highest point on the wave will be at  and the lowest at ; however, if you then begin to shift the equation vertically by adding values, as in, , then you need to account for said shift. This would make the minimum value to be  and the maximum value to be .

For our question, the range of values covers . This range is accomplished by having either  or  as your coefficient. ( merely flips the equation over the -axis. The range "spread" remains the same.) We need to make the upper value to be  instead of . To do this, you will need to subtract , or , from . This requires an downward shift of .  An example of performing a shift like this is:

Among the possible answers, the one that works is:

The  parameter does not matter, as it only alters the frequency of the function.

The range of a cosine wave is altered by the coefficient placed in front of the base equation. So, if you have , this means that the highest point on the wave will be at  and the lowest at ; however, if you then begin to shift the equation vertically by adding values, as in, , then you need to account for said shift. This would make the minimum value to be  and the maximum value to be .  

For our question, the range of values covers . This range is accomplished by having either  or  as your coefficient. ( merely flips the equation over the -axis. The range "spread" remains the same.) We need to make the upper value to be  instead of . This requires an upward shift of . An example of performing a shift like this is:

Among the possible answers, the one that works is:

The range of a sine or cosine function spans from the negative amplitude to the positive amplitutde. The amplutide is given by  in the equation . Thus the range for our function is 

For the sine and cosine funcitons, the range is equal to the negative amplitude to the positive amplitude.

The amplitude is found by taking  from the general equation: 

.

We see in our equation that 

(when no coefficient is written, it is a 1).

Thus we get that the amplitude is 

The range of the function represents the spread of possible answers you can get for , given all values of . In this case, the ordinary range for a cosine function is , since the largest value that cosine can solve to is  (for a cosine of  or a multiple of one of those values), and the smallest value cosine can solve to is  (for a cosine of  or a multiple of one of those values).

However, in this case our final answer is increased by  after the cosine is applied to . This results in a final range of  to  (or, in other words,  to , plus ).

So, our final range is .

The range of the function represents the spread of possible answers you can get for , given all values of . In this case, the ordinary range for a cosine function is , since the largest value that cosine can solve to is  (for a cosine of  or a multiple of one of those values), and the smallest value cosine can solve to is  (for a cosine of  or a multiple of one of those values).

However, in this case our final answer is multiplied by -3 after the cosine is applied to . This results in a final range of  to  (or, in other words,  to , multiplied by ).

So, our final range is .

The range of the function represents the spread of possible answers you can get for , given all values of . In this case, the ordinary range for a cosine function is , since the largest value that cosine can solve to is  (for a cosine of  or a multiple of one of those values), and the smallest value cosine can solve to is  (for a cosine of  or a multiple of one of those values).

However, in this case our final answer is first multiplied by , then decreased by  after the cosine is applied to . Multiplying the initial  range by  results in a new range of . Next, subtracting  from this range gives us a new range of .

Note that the  does not change our range. This is because, irrespective of other multipliers, a cosine operation can only return values between  and . To think of this a different way,  will give us the same returns as , only we will move around the unit circle five times as much before finding our answer.

Thus, our final range is .

The range of the function represents the spread of possible answers you can get for , given all values of . In this case, the ordinary range for a cosine function is , since the largest value that cosine can solve to is  (for a cosine of  or a multiple of one of those values), and the smallest value cosine can solve to is  (for a cosine of  or a multiple of one of those values).

One fast way to match a range to a function is to look for the function which has a vertical shift equal to the mean of the range values. In other words, for the standard trigonometric function , where  represents the vertical shift, .

In this case, since our range is , we expect our  to be .

Of the answer choices, only  has , so we know this is our correct choice.

The range of the function represents the spread of possible answers you can get for , given all values of . In this case, the ordinary range for a cosine function is , since the largest value that cosine can solve to is  (for a cosine of  or a multiple of one of those values), and the smallest value cosine can solve to is  (for a cosine of  or a multiple of one of those values).

One fast way to match a range to a function is to look for the function which has a vertical shift equal to the mean of the range values. In other words, for the standard trigonometric function , where  represents the vertical shift, .

In this case, since our range is , we expect our  to be .

Of the answer choices, only  has , so we know this is our correct choice.