Where does the pythagorean identity sin2 θ + cos2 θ = 1 come from? how would you use it to find the sine cosine and tangent values of the angle?

Imagine a trigonometric circle with radius equal to 1.

We can say that the opposite side of the angle generated by the origin is equal to sen Ф and the adjacent equal to cos Ф

With this we can say that:

h² = c² + c²

If r = 1, then h = 1

1² = cos² + sen²

1 = cos² Ф + sen² Ф

You can use this equation a lot of times because it's the fundamental trigonometric relation
, so, when you something like:

sen Ф = cos Ф + 1

you can take from sen² Ф + cos² Ф = 1 that and then resolve.

a is the correct

i believe the correct answer is option 4.principalities were small territories that were run by russian rulers.

which statement correctly defines principalities in northern asia in the 1200s? principalities were small territories that were run by russian rulers.

hope i could ! : )