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Can't do math.
1. By the way, can you find the position of the angle -π/3 in the rectangular coordinate system?

Sine value = opposite edge/bevel edge

You just need to remember.

The hypotenuse is always positive (greater than 0)

Then you have to look across the street.

If the coordinates corresponding to the opposite side are positive

Then the sine value is positive

If it is negative

That's negative

of course

This just distinguishes between positive and negative. The next thing you need to do is to remember the sine and cosine of a special angle. Don't ask how it came from. If you want to ask, you have to start from the zero of the university mathematics department (that is, 1+ 1=2, the same reason).

2. Really?

This COS (1500) = COS (60)

You want to.

360 is a circle. You turn it four times, but it still goes back to its original place.

Then the method is the same as that in 1.

tan(-7π/4)

The difference is that it can find the equivalent in half a circle.

Just draw more rectangular coordinate systems.

Find the angle from 0 to 2π according to the following conditions.

sinα=-√3/2

How's this?

Is a sine and cosine function of a specific angle.

Come on, remember! ! ! There is no other way.

Just remember √2= 1.4 14.

√3= 1.732

√5=2.236.。 .

Attach a special angle trigonometric function value.

0 degrees

sina=0,cosa= 1,tana=0

30 degrees

sina=0,cosa=√3/2,tana=√3/3

45 degrees

sina=√2/2,cosa=√2/2,tana= 1

60 degrees

sina=√3/2,cosa= 1/2,tana=√3

90 degrees

Sina= 1, cosa=0, tana does not exist.

120 degrees

sina=√3/2,cosa=- 1/2,tana=-√3

150 degrees

sina= 1/2,cosa=-√3/2,tana=-√3/3

180 degrees

sina=0,cosa=- 1,tana=0

270 degrees

Sina=- 1, cosa=0, tana does not exist.

360 degrees

sina=0,cosa= 1,tana=0