# GEOMETRY HELP PLEASE ! 10 POINTS FOR BEST ANSWER ; PLEASE !?

Which of the following is the basis of the proof that sin2 x + cos2 x = 1?

A. trigonometric identity, which states that tan x = (sin x/cos x)

B. Law of Sines and Law of Cosines

C. equation of a circle with (0, 0) as its center and radius = 1

D. definition of the tangent ratio

### 2 Answers

- Anonymous10 years agoFavorite Answer
Answer is C. I don't have much ability to explain it in English sorry.

Found something on Wikipedia about unit circle.

f (x, y) is a point on the unit circle in the first quadrant, then x and y are the lengths of the legs of a right triangle whose hypotenuse has length 1. Thus, by the Pythagorean theorem, x and y satisfy the equation

x2 + y2 = 1.

The equation x2 + y2 = 1 gives the relation

cos^2(t) + sin^2(t) = 1

Source(s): http://en.wikipedia.org/wiki/Unit_circle - 3 years ago
first you would possibly want to discover the mid factors of PR and QR to get the measurements of M and N and also you try this with the aid of the midpoint formulation it is X1+X2 divided with the aid of two and Y1+Y2 divided with the aid of two and also you ought to get M=(5,4) and N=(9.5,4) Then to discover MN and PQ you should use the gap formulation it is the sq. direction of (X1-X2)^2+(Y1-Y2)^2 and also you ought to get MN= 4.5 and PQ= 9. those lengths evaluate to eachother because PQ=2MN or MN=PQ/2. this signifies that MN is the midsegment of triangle PQR. i desire this helps!