What is the value of \(\frac{{tan9^\circ tan23^\circ tan60^\circ tan67^\circ tan81^\circ }}{{cosec{^2}72^\circ + {{\cos }^2}15^\circ - {{\tan }^2}18^\circ + {{\cos }^2}75^\circ }} \)
What is the value of \(\frac{{tan9^\circ tan23^\circ tan60^\circ tan67^\circ tan81^\circ }}{{cosec{^2}72^\circ + {{\cos }^2}15^\circ - {{\tan }^2}18^\circ + {{\cos }^2}75^\circ }} \) Correct Answer <span class="math-tex">\(\frac{\sqrt 3}{2}\)</span>
Formulae used :
[ alt="Trigo - Formula" src="//storage.googleapis.com/tb-img/production/21/02/Trigo%20-%20Formula.PNG" style="width: 450px; height: 202px;">
tanθ = 1/cotθ, Cosec2θ – cot2θ = 1 and cos2θ + sin2θ = 1
[ alt="Trigo - Angles and Radian" src="//storage.googleapis.com/tb-img/production/21/02/Trigo%20-%20Angles%20and%20Radian.PNG" style="width: 392px; height: 218px;">
Calculations :
tan 9° tan 23° tan 60° tan 67° tan 81°/cosec272° + cos215° - tan218° + cos275°
= cot81° cot67° tan60° tan67° tan81°/cosec272 - cot272° + cos215° + sin215°
= tan60°/(1 + 1)
= √3/2
∴ The required value will be √3/2