# Prove the Following. Tan 3 θ − 1 Tan θ − 1 = Sec 2 θ + Tan θ - Geometry

Sum

Prove the following.

$\frac{\tan^3 \theta - 1}{\tan\theta - 1} = \sec^2 \theta + \tan\theta$

#### Solution

$\frac{\tan^3 \theta - 1}{\tan\theta - 1}$

$= \frac{\left( \tan\theta - 1 \right)\left( \tan^2 \theta + \tan\theta \times 1 + 1 \right)}{\tan\theta - 1} \left[ a^3 - b^3 = \left( a - b \right)\left( a^2 + ab + b^2 \right) \right]$

$= \tan^2 \theta + \tan\theta + 1$

$= \sec^2 \theta + \tan\theta \left( 1 + \tan^2 \theta = \sec^2 \theta \right)$

Concept: Application of Trigonometry
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#### APPEARS IN

Balbharati Mathematics 2 Geometry 10th Standard SSC Maharashtra State Board
Chapter 6 Trigonometry
Problem Set 6 | Q 5.09 | Page 138