Why does sine squared plus cosine squared equal 1?

How on earth is 1-cos(x) equal to 2sin^2(x/2)?

1-cosx = 2sin^2(x/2) trigonometric identites proof || 1-cos theta

Prove that 1+cosx=2cos^2(x/2) and 1-cosx=2sin^2(x/2) trigonometric identites

PreCalculus - Trigonometry: Trig Identities (31 of 57) Proof cos^2(x)=(1+cos2x)/2

Integral 1/cos^2(x)

PreCalculus - Trigonometry: Trig Identities (30 of 57) Proof sin^2(x)=(1-cos2x)/2

Prove (1-cos^2x)/sinx=sinx

30 分で学ぶ三角法 • A レベル数学、Pure Year 2、第 6 章と第 7 章 📚

Limit Trigonometric Function (1 - cos2x)/x^2 Half angle Formula application

1+cosx=2cos^2(x/2) trigonometry identites solve || 1+cos(theta)

Integral of (1 - cos 2x)/(1 + cos 2x)

Find the limit as x approaches 0 of (1- cos 2x)/(2 sin^2 x)

Limit of (1-cos(x))/x as x approaches 0 | Derivative rules | AP Calculus AB | Khan Academy

proof that sin^2(x)=(1-cos2x)/2 || 1-cos2x=2sin^2 x

#Trigonometry all formulas

cos^2(1 + tan^2) = 1

Simplify Trig Expression (1-cos(2x))/sin(x) - Find an Identity

Complex Analysis: Integral of (1-cos(x))/x^2 using Contour Integration

(Method 2) Integral of 1/(1+cos^2(x)) (substitution + substitution)