Chapter 8: Q. 25 (page 516)

Find the exact value of the expression-
$\tan 20 ° - \frac{\cos 70 °}{\cos 20 °}$

Short Answer

Expert verified

The required value is,

$\tan 20 ° - \frac{\cos 70 °}{\cos 20 °} =$ $0$

Step by step solution

Step 1. Given information

Given expression,

$\tan 20 ° - \frac{\cos 70 °}{\cos 20 °}$

Step 2. Calculation

Solving the given expression,

$\tan 20 ° - \frac{\cos 70 °}{\cos 20 °} = \frac{\sin 20 °}{\cos 20 °} - \frac{\cos 70 °}{\cos 20 °}$ ---------- $(\tan θ = \frac{\sin θ}{\cos θ})$

$= \frac{\sin 20 ° - \cos 70 °}{\cos 20 °} = \frac{\sin (90 ° - 70) - \cos 70 °}{\cos 20 °} = \frac{\cos 70 ° - \cos 70 °}{\cos 20 °} = 0$ ----------- $\{\sin (90 ° - θ) = \cos θ\}$

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Find the exact value of the expression-
$\tan 20 ° - \frac{\cos 70 °}{\cos 20 °}$

Short Answer

Step by step solution

Step 1. Given information

Step 2. Calculation

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Find the exact value of the expression-tan20°-cos70°cos20°

Short Answer

Step by step solution

Step 1. Given information

Step 2. Calculation

One App. One Place for Learning.

Most popular questions from this chapter

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Study anywhere. Anytime. Across all devices.

Find the exact value of the expression-
$\tan 20 ° - \frac{\cos 70 °}{\cos 20 °}$