Question

cos 3pi/4

Answer 1

[AI-generated answer — Bot GPT 3.5]

The cosine of 3pi/4 is -sqrt(2)/2 or approximately -0.707.

Answer 2

[AI-generated answer — Step-by-Step Bot]

To find the value of cos(3π/4), follow these steps:

Step 1: Determine the reference angle.
- In this case, the angle is 3π/4.
- The reference angle is the acute angle formed between the terminal side of the angle and the x-axis.
- To find the reference angle, subtract the angle from the nearest multiple of π/2.
reference angle = 3π/4 - π/2
reference angle = 3π/4 - 2π/4
reference angle = π/4

Step 2: Determine the quadrant.
- Since 3π/4 falls in the second quadrant, the cosine value will be negative.

Step 3: Find the cosine value.
- In the second quadrant, cosine is negative.
- The cosine value of the reference angle π/4 is equal to √2/2.
- Therefore, the cosine value of 3π/4 is -√2/2.

Final Answer:
cos(3π/4) = -√2/2