Verified answer

this is true because sine is the y value of a triangle divided by the radius (hypotenuse) of a triagle when drawn on a standard xy plane.

So for the first and second quadrants the y value will be the same for any 2 triangles that are opposit of eachother 1-179 60-120 45-135 anything. And the hypotenuse is always positve so you have 2 positive number with the same value.

This would be easier to explain with a diagram.

draw line from origin out to (3,4) then drop a line straight down to the x axis making a triangle. now do the smae with (-3,4)

Same triangle with a different x value. And the hypotenuse of both is 5. SO the sine is y/r

or 4/5 for both of them.

Another way to see is graph the function on a calculator from 0 to 180 and youll see it makes a hump shape going up til 90 and then back tozero by 180.

Soory so damn detailed the sine cosine and tangent functions are very interesting and beautiful!

Yes. In general, sin(180 - x) = sin(x) in degrees, or in radians sin(pi - x) = sin(x).

And this is true even for x outside the range of 0 - 180 degrees.

Yes, what you're saying is correct and this is because the sine rule is positive in the first and the second quadrants of the CAST Rule.

theoreticly it is

sin60=sin pi/3=sqrt3 / 2

sin120=sin 90+30 =sin (pi /2 +pi /6)

also is sin (pi /2 +some angle) =cos (some angle)

sin 120 = cos (pi /6 )=sqrt3 / 2

and sin120=sin60

YES, exactly

Sin120º = 0,86602540378443864676372317075294 = (3^0.5)/2

Sin60º = 0,86602540378443864676372317075294 = (3^0.5)/2

True

yes its true.

But you could have checked it with a calculator.....