Prove that:
sin 40° + sin 20° = cos 10°
[3] Trigonometric Functions
Chapter: [3] Trigonometric Functions
Concept: undefined >> undefined
Prove that:
cos 55° + cos 65° + cos 175° = 0
[3] Trigonometric Functions
Chapter: [3] Trigonometric Functions
Concept: undefined >> undefined
Prove that:
sin 50° − sin 70° + sin 10° = 0
[3] Trigonometric Functions
Chapter: [3] Trigonometric Functions
Concept: undefined >> undefined
Prove that:
cos 80° + cos 40° − cos 20° = 0
[3] Trigonometric Functions
Chapter: [3] Trigonometric Functions
Concept: undefined >> undefined
Prove that:
cos 20° + cos 100° + cos 140° = 0
[3] Trigonometric Functions
Chapter: [3] Trigonometric Functions
Concept: undefined >> undefined
Prove that:
\[\sin\frac{5\pi}{18} - \cos\frac{4\pi}{9} = \sqrt{3} \sin\frac{\pi}{9}\]
[3] Trigonometric Functions
Chapter: [3] Trigonometric Functions
Concept: undefined >> undefined
Prove that:
\[\cos\frac{\pi}{12} - \sin\frac{\pi}{12} = \frac{1}{\sqrt{2}}\]
[3] Trigonometric Functions
Chapter: [3] Trigonometric Functions
Concept: undefined >> undefined
Prove that:
sin 80° − cos 70° = cos 50°
[3] Trigonometric Functions
Chapter: [3] Trigonometric Functions
Concept: undefined >> undefined
Prove that:
sin 51° + cos 81° = cos 21°
[3] Trigonometric Functions
Chapter: [3] Trigonometric Functions
Concept: undefined >> undefined
Prove that:
\[\cos\left( \frac{3\pi}{4} + x \right) - \cos\left( \frac{3\pi}{4} - x \right) = - \sqrt{2} \sin x\]
[3] Trigonometric Functions
Chapter: [3] Trigonometric Functions
Concept: undefined >> undefined
Prove that:
\[\cos\left( \frac{\pi}{4} + x \right) + \cos\left( \frac{\pi}{4} - x \right) = \sqrt{2} \cos x\]
[3] Trigonometric Functions
Chapter: [3] Trigonometric Functions
Concept: undefined >> undefined
Prove that:
\[\sin 65^\circ + \cos 65^\circ = \sqrt{2} \cos 20^\circ\]
[3] Trigonometric Functions
Chapter: [3] Trigonometric Functions
Concept: undefined >> undefined
Prove that:
sin 47° + cos 77° = cos 17°
[3] Trigonometric Functions
Chapter: [3] Trigonometric Functions
Concept: undefined >> undefined
Prove that:
cos 3A + cos 5A + cos 7A + cos 15A = 4 cos 4A cos 5A cos 6A
[3] Trigonometric Functions
Chapter: [3] Trigonometric Functions
Concept: undefined >> undefined
Prove that:
cos A + cos 3A + cos 5A + cos 7A = 4 cos A cos 2A cos 4A
[3] Trigonometric Functions
Chapter: [3] Trigonometric Functions
Concept: undefined >> undefined
Prove that:
`sin A + sin 2A + sin 4A + sin 5A = 4 cos (A/2) cos((3A)/2)sin3A`
[3] Trigonometric Functions
Chapter: [3] Trigonometric Functions
Concept: undefined >> undefined
Prove that:
sin 3A + sin 2A − sin A = 4 sin A cos \[\frac{A}{2}\] \[\frac{3A}{2}\]
[3] Trigonometric Functions
Chapter: [3] Trigonometric Functions
Concept: undefined >> undefined
Prove that:
cos 20° cos 100° + cos 100° cos 140° − 140° cos 200° = −\[\frac{3}{4}\]
[3] Trigonometric Functions
Chapter: [3] Trigonometric Functions
Concept: undefined >> undefined
Prove that:
\[\sin\frac{x}{2}\sin\frac{7x}{2} + \sin\frac{3x}{2}\sin\frac{11x}{2} = \sin 2x \sin 5x .\]
[3] Trigonometric Functions
Chapter: [3] Trigonometric Functions
Concept: undefined >> undefined
Prove that \[\cos x \cos \frac{x}{2} - \cos 3x \cos\frac{9x}{2} = \sin 7x \sin 8x\]
[3] Trigonometric Functions
Chapter: [3] Trigonometric Functions
Concept: undefined >> undefined
