Видео ютуба по тегу Prove That Cos12° Cos84° Cos132° Cos156°=-1

The value of cos 12^∘+cos 84^∘+cos 156^∘+cos 132^∘ is: (a) 1/8 (b) -1/2 (c) 1 (d) 1/2

Prove that \( \cos 12^{\circ}+\cos 60^{\circ}+\cos 84^{\circ}=\cos 24^{\circ}+\cos 48^{\circ} \)...

Prove that : \[ \cos 15^{\circ}-\sin 15^{\circ}=\frac{1}{\sqrt{2}} \]

Prove that sin 18^∘ and cos 36^∘ are the roots of the equation : 4 x^2-2 √(5) x+1=0

cos 12^∘/sin 78^∘+tan 23^∘/ 67^∘=? (a) 0 (b) 1 (c) 2 (d) 3/2

The value of cos 12^∘cos 24^∘cos 36^∘cos 48^∘cos 60^∘cos 72^∘cos 84^∘ is : (a) 1/64 (b) 1/128 (c)...

Add the following algebraic expressions : 2a - 3b + 4c , -3a + 2b - 5c , 7a - c and 3b + 6c | ...

If for real values of x, cosθ=x+1/x, then (A) θ is an acute angle (B) θ is right angle (C) θ is a...

The value of 70^∘+4 cos 70^∘ is (1) 1/√(3) (2) √(3) (3) 2 √(3) (4) 1/2

The value of \( \cos ^{2} 76^{\circ}+\cos ^{2} 16-\cos 76^{\circ} \cos 16^{\circ} \), is (A) \( ...

The value of \( \cos 12^{\circ} \cos 24^{\circ} \cos 36^{\circ} \cos 48^{\circ} \cos 72^{\circ} ...