Trig - cast method

What happens when you have something like sin(x) = 0 ? Where would you draw the lines if the angle is 0 degrees? Should the angles be in the positive or negative quadrants? How do i find the values of x

I know you can find them easily with the graph, but pls, man wants to know how to do it with this method. Safe.

Posted from TSR Mobile

Guys, pls. All i would like to know is where and in which quadrants i would draw the lines for the angles, when an angle is 0 degrees.
Safe yo


Posted from TSR Mobile

There are 2 answers to this that I can think of:

(i) CAST tells you in which regions sin, cos, tan etc are +ve or -ve. But 0 isn't +ve or -ve so CAST is irrelevant! Just remember that sin 0 = 0 and use the basic facts that sin(360 + x) = sin x and sin(180 - x) = sin x to get the other solutions.

(ii) CAST tells you in which regions sin, cos, tan etc are +ve or -ve. 0 isn't +ve or -ve, but in a sense it is both. In the C region sin is -ve but in the A region sin is +ve, To get from -ve to +ve you have to go through 0, so one line is the +ve x-axis which separates the C region from the A region.

In the A region sin is +ve and in the S region sin is +ve, so nothing to do here.

In the S region sin is +ve and in the T region sin is -ve. To get from +ve to -ve you have to go through 0. So you can draw another line separating the S region from the T region, i.e. the negative x-axis.

In the T region and C region sin is -ve, so there's nothing to do here.

So you've got your two lines which basically form the x-axis (0 degrees and 180 degrees, and multiples thereof). In other words, the lines aren't in a quadrant - they're the boundaries of quadrants!