Why does cos (120°) = -1/2? How does one work it out without a calculator?
Why does cos (-120°) = -1/2? How does one work it out without a calculator?
Why cos (-150) is equal to +cos(150) and not equal to -cos(150)? How can I find value of cos37°? What is value of cos 45/2? Show that cos^2 (45°)-sin^2 (15°) = √3/4? What is the reason -40 Fahrenheit the same as -40 Celsius? How's the conversion work to get the same number at -40? How can you calculate sin, cos, and tan without a calculator? What is the value of Sin37°.cos53°? What is the value of cos 1? I need to state the difference between 10-20 Celsius in Fahrenheit. Why do I get it right by simply multiplying with 1.8? Why shouldn't I add +32? Does cos x = 0 always imply that sin x = 1? What is the value of cos9*? How can the negative reciprocal of a number be found on a calculator? What is the value of 1+1°=? How do I solve 1/6^0.4 without the use of calculator? Why can't we just add 32 degrees to get from Celsius to Fahrenheit? Why does it have to be more complicated? Why is [math]\cos (30^\circ)[/math] equal to [math]\cos (-330^\circ)[/math]? Trigonometry (mathematics): How does the tan inverse of -8/6 = -53.13°? How do I calculate 1/6^0.4 without the use of calculator? Why does the Fahrenheit conversion offset by 32? Is there a way to do sin, cos, and tan without a calculator? Why is Co(CO) 4 tetrahedral and diamagnetic? Why does 1/3 of 1/3 equal 1? What is the value of sec^-1 (cos (-3/5))? What is the answer to 2 1/2 (-3 3/4)? Does 1/3 + 1/3 + 1/3=1,  or .999 when converted to decimals? What is cos(z)=? Where z is complex number. Why is CO2 non-polar? What is cos(z) =? Where z is complex number? Why is 1+1 equal to 2 but not 11? Are 1/2 and 2/4 the same number?