The Exact Value of cot 22.5 degrees (5 of 5)

The exact value of cot 22.5deg = 1+√2, can be solve by using the cotangent function's double-angle formula cot [2(theta)] = {[(cot theta)^2] -1}/[2(cot theta)], where theta = 22.5deg, in which we can find a quadratic equation. By employing the Quadratic Formula, we can then find the exact value of cot 22.5deg = 1+√2.

Mharthy's Channel's Playlists:

Differential Calculus    • Prove f'(x) = nx^(n-1), if f(x) = x^n...  

Complex Numbers    • Prove:⁡⁡  (a⁡+⁡b⁡i)(c⁡+⁡d⁡i)⁡ = ⁡(ac⁡...  

Conversions    • Conversions  

Logarithms, etc.    • Logarithms, etc.  

Analytic Geometry    • Analytic Geometry  

Plane Trigonometry Basics    • Plane Trigonometry Basics  

Fractions    • Fractions  

Systems of first degree/linear equations    • Systems of first degree/linear equations  

Exponents and Radicals    • Exponents and Radicals  

Quadratic Equation and Formula, etc.    • Quadratic Equation and Formula, etc.  

Division of Polynomials, etc.    • Division of Polynomials, etc.  

The Binomial Theorem    • The Binomial Theorem  

Trigonometric Formulas    • Trigonometric Formulas  

The Exact Values of sin & cos Functions of a Right Triangle    • The Exact Values of sin and cos Funct...  

Trigonometric Identities 1    • Trigonometric Identities 1  

Trigonometric Identities 2    • Trigonometric Identities 2  

Trigonometric Identities 3    • Trigonometric Identities 3