Question

1. Evaluate :
sin 18°/cos 72°​

Answer 1

Answer:

$\frac{ \sin(18) }{ \cos(90 - 18) } \\ as \: \cos(90 - \alpha ) = \sin( \alpha ) \\ \frac{ \sin(18) }{ \sin(18) } = 1$

Answer 2

Step-by-step explanation:

$\text{ \large \underline{ \orange{Question:-}}}$

• 1. Evaluate :sin 18°/cos 72°

$\text{ \large \underline{ \green{Given:-}}}$

• sin 18°/cos 72°

$\text{ \large \underline{ \pink{To Find:-}}}$

• Find the simplify the number .

$\text{ \large \underline{ \red{Solution:-}}}$

$\sf \to \frac{sin 18°}{cos72°} \: \\ \\ \sf \to \frac{sin(90° - 18°)}{cos72°} \\\\ \: \sf \to sin(90 - a) = cos(a) \\\\ \sf \to \frac{cos72°}{cos72°} \: \\ \\ \sf \to \blue{ 1 }$

$\text{ \large \underline{ \purple{more information:-}}}$

• 1. sin (-x) = -sin x

• 2. cos (-x) = cos x

• 3. tan (-x) = -tan x

• 4. cosec (-x) = -cosec x

• 5. sec (-x) = sec x

• 6. cot (-x) = -cot x