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  • Trigonometry
  • Trigonometric identities test
  • Sum to product formulas

Sum to product formulas

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  • Question 1:
    1 pts
    Express cos2βcos8β\cos 2\beta -\cos 8\beta as a product.
    sin10βsin6β\sin 10\beta \sin 6\beta
    2sin10βsin6β2\sin 10\beta \sin 6\beta
    2sin5βsin3β2\sin 5\beta \sin 3\beta
    sin5βsin3β\sin 5\beta \sin 3\beta
  • Question 2:
    1 pts
    Express sin10M+sin4M\sin 10M +\sin 4M as a product.

    2sin7Mcos3M-2\sin 7M\cos 3M

    sin7Mcos3M\sin 7M\cos 3M

    12sin7Mcos3M\dfrac{1}{2} \sin 7M\cos 3M

    2sin7Mcos3M2\sin 7M\cos 3M

  • Question 3:
    1 pts
    Express sin(π4+α)+sin(π4α)\sin \left(\dfrac{\pi}{4}+\alpha\right)+\sin \left(\dfrac{\pi}{4}-\alpha\right) as a product.

    2sinα\sqrt{2}\sin \alpha

    2cosα\sqrt{2}\cos \alpha

    cosα\cos \alpha

    sinα\sin \alpha

  • Question 4:
    1 pts
    sin(α+β)sin(αβ)=2cosβsinα\sin(\alpha+\beta)-\sin(\alpha-\beta)=2\cos \beta \sin\alpha
  • Question 5:
    2 pts
    Expresssin20+cos50\sin 20^{\circ}+\cos 50^{\circ} as a product.

    cos40\cos 40^{\circ}

    cos30\cos 30^{\circ}

    cos20\cos 20^{\circ}

    cos10\cos 10^{\circ}

  • Question 6:
    2 pts
    Simplify the expression using sum to product formulas.
    sin20+sin34+sin24+sin30=\sin 20^{\circ}+ \sin 34^{\circ}+\sin 24^{\circ}+\sin 30^{\circ}=
  • Question 7:
    2 pts
    Express cosα+cos3α+cos5α+cos7α\cos \alpha+\cos 3\alpha+\cos 5\alpha+\cos 7\alpha as a product.
    cosαcos2αcos4α\cos\alpha \cos 2\alpha \cos 4\alpha
    4cosαcos2αcos4α4\cos\alpha \cos 2\alpha \cos 4\alpha
    4cosαcos6αcos8α4\cos\alpha \cos 6\alpha \cos 8\alpha
    none of these
  • Question 8:
    2 pts
    sin75+sin15=62\sin 75^{\circ}+\sin 15^{\circ}=\dfrac{\sqrt{6}}{2}
  • Question 9:
    3 pts
    Find the exact value of the expression.1+cosx1+\cos x

    2cos2x2\cos^{2} x

    2tan2(x2)2\tan^{2}\left(\frac{x}{2}\right)

    2sin2(x2)2\sin^{2}\left(\frac{x}{2}\right)

    2cos2(x2)2\cos^{2}\left(\frac{x}{2}\right)

  • Question 10:
    3 pts
    Find the exact value of the expression.
    sec7(sin47+sin61sin11sin25)= \sec7^{\circ}(\sin 47^{\circ}+\sin 61^{\circ}-\sin 11^{\circ}-\sin25^{\circ})=
  • Question 11:
    3 pts
    Find the exact value of the expression.
    cos40+cos40cos20sin20=\dfrac{\cos 40^{\circ} + \cos 40^{\circ}-\cos 20^{\circ}}{\sin 20^{\circ}}=
  • Question 12:
    3 pts
    Express as a product. tan40+cot40\tan 40^{\circ}+\cot 40^{\circ}
    2cos20\dfrac{2}{\cos 20^{\circ}}
    2cos10\dfrac{2}{\cos 10^{\circ}}
    1cos10\dfrac{1}{\cos 10^{\circ}}
    2sin10\dfrac{2}{\sin 10^{\circ}}