Negative gradients with m= tan theta?

Question

What is the angle the line y= -2x- 4 makes with the x axis? I tried using m= tan theta but I got a negative answer.

Answer 1

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Answer 2

you got a negative answer because m itself is negative and tan (-2) would be negative as well. This happens as the angle it makes with x axis is below the axis. You get -63.43 degrees right? if you wanna find just the angle, then just take the abs value, 63.43 degrees will do.

Answer 3

y=mx+c

m=tan(theta)

here we have

m=-2

tan(theta)=-2

theta=(pi)+taninverse(-2)=180+(-63.43)

theta=116.57

because tan(theta) will always give negative value only in second and fourth quadrant