Buktikan setiap identitas trigonometri berikut

Buktikan setiap identitas trigonometri berikut

Penjelasan dengan langkah-langkah:

$sin^{4} ( θ) - cos^{4} ( θ ) = 1 - 2 cos^{2} ( θ) \ sin^{4} ( θ ) - cos^{4} ( θ ) = (sin^{2} (θ ) - cos^{2} ( θ ))(sin^{2} ( θ ) + cos^{2} ( θ )) \ = sin^{2} ( θ ) - cos^{2} ( θ) \ = 1 - cos^{2} ( θ) - cos^{2} ( θ) \ = 1 - 2cos^{2} ( θ)$

$sec^{4} (θ) - sec^{2} (θ) = tan^{4} (θ) + tan^{2} (θ) \ = (sec^{2} (θ) - 1)sec^{2} (θ) \ =tan^{2} (θ)sec^{2} (θ) \ = tan^{2}(θ)(1 + tan^{2}(θ)) \ = tan^{2}(θ) + tan^{4}(θ)$