Question

Prove that sin10+sin20+sin40+sin50-sin70-sin80 = 0 A/L MATHEMATICS. DON'T WRITE RUBBISH, IF YOU WRITE YOU WILL BE REPORTED. ANSWER FOR POINTS....

Answer 1

Answer:

sin10°+sin20°+sin40°+sin50°-sin70°-sin80° = 0 ... Proved.

Step-by-step explanation:

We have to prove that

sin10°+sin20°+sin40°+sin50°-sin70°-sin80° = 0 ........(1)

Now, left hand side of equation (1)

= (sin10°+sin20°) + (sin40°+sin50°) - (sin70°+sin80°)

=2 sin 15°cos5° +2 sin45°cos5° - 2 sin75°cos5°

{Applying the formula, SinA+SinB= 2Sin $\frac{A+B}{2}$Cos$\frac{A-B}{2}$}

=2cos5° (sin15° + sin 45° - sin75°)

=2cos5° {-(sin75°-sin15°) + sin45°}

=2cos5° {-2sin45°cos30° + sin45°}

=2 cos5°{-2($\frac{1}{\sqrt{2}}$)($\frac{1}{2}$)+ $\frac{1}{\sqrt{2}}$}

=2cos5° (0)

=0

=Right hand side of equation (1).

(Hence, proved)

Answer 2

Answer:

0 is the right answer

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