When is the odd even symbol in senior one mathematics? Look at the quadrant. The most important thing is that parity remains the same. I don't know what to think. .
Fifth floor. Parity refers to odd or even multiples of half π. Changing or unchanging means that the trigonometric function name remains unchanged. If it is an odd multiple of half π, the trigonometric function name will change, sin will change to cos, and cos will change to sin. If it is an even multiple, it remains unchanged. Symbols refer to signs. For example, sin(x+π/2)=cosx, because it is followed by half π 1 times, which is an odd multiple, so sin should become cos. Suppose x is [0,90], then X+π/2 is [sin 180], then sin90.