Consider the complex numberz=3(cos(355∘)+isin(355∘)). Which of the following complex numbers best approximates z ?Choose 1 answer:(A) 3−0.3i(B) 0.3+3i(C) 3+0.3i(D) 0.3−3i
Q. Consider the complex numberz=3(cos(355∘)+isin(355∘)). Which of the following complex numbers best approximates z ?Choose 1 answer:(A) 3−0.3i(B) 0.3+3i(C) 3+0.3i(D) 0.3−3i
Convert to radians: Convert the given angle from degrees to radians.Since we are dealing with trigonometric functions, we need to convert the angle 355 degrees to radians. The conversion factor is π radians = 180 degrees. Therefore, 355 degrees is (355/180)π radians.
Evaluate cosine and sine: Evaluate the cosine and sine of the angle in radians.Using a calculator or trigonometric tables, we find the values of cosine and sine for the angle close to 355 degrees (which is close to 360 degrees or 2π radians). We know that cos(360°)=1 and sin(360°)=0. Since 355° is close to 360°, cos(355°) will be slightly less than 1 and sin(355°) will be slightly greater than 3600 but still very small.
Approximate cosine and sine: Approximate the values of cosine and sine for 355 degrees.Given that 355 degrees is very close to 360 degrees, we can approximate:cos(355∘)≈1 (slightly less)sin(355∘)≈0 (slightly more)
Multiply by modulus: Multiply the approximated cosine and sine values by the modulus of the complex number.The modulus of the complex number z is 3. Therefore, we multiply the approximated values of cosine and sine by 3:Real part: 3×cos(355°)≈3×1≈3Imaginary part: 3×sin(355°)≈3×0≈0 (but slightly positive)
Choose best match: Choose the answer that best matches the approximated real and imaginary parts.Looking at the options, we need a real part close to 3 and an imaginary part that is positive but very small. The best match is:(C) 3+0.3i
More problems from Compare linear, exponential, and quadratic growth