What is the value of cos(90°30') approximately given that 1° = 0.0175?

• A. -0.0082
• B. -0.0087
• C. 0.0087
• D. 0.0081

To find the value of cos(90°30'), we first need to convert the angle into radians. Since 1° is approximately 0.0175 radians, we can calculate:

Conversion of Degrees to Radians

90°30' can be expressed as:

• 90° + 30' = 90° + 30/60° = 90.5°

Now, converting 90.5° to radians:

90.5° × 0.0175 = 1.58 radians (approximately).

Calculating Cosine

Now, we find the cosine of 1.58 radians. The cosine function is known to be close to zero around 90° (or π/2 radians), but slightly negative for angles greater than 90°.

Approximate Value

Using a calculator or cosine table, we find:

• cos(90.5°) ≈ -0.0087

Final Answer

Thus, the value of cos(90°30') is approximately -0.0087, which corresponds to option B.