
William W. answered 06/20/22
Experienced Tutor and Retired Engineer
Just pick some random values for u and v, like u = 45° and v = 30°
tan(45 - 30) = tan(15) and using my calculator tan(15) = 0.2679
and again using my calculator tan(45) - tan(30) = 1 - 0.5774 = 0.4226
Since 0.2679 ≠ 0.4226, tan(45 - 30) ≠ tan(45) - tan(30)
If you need to use exact values instead of calculator values, you'll need to use the difference identity for tangent to get the exact value of tan(15). Use the unit circle to get the exact for tan(45) and tan(30)