Sin(a-30)-sin(a+30)=-coss

Mathematics

1 answer:

Dafna11 [192]3 years ago

8 0

Answer:

We know that:

Sin(a + b) = sin(a)*cos(b) + sin(b)*cos(a)

Then if we use this property in our expression:

sin(a-30)-sin(a+30)

We get:

sin(a)*cos(-30°) + sin(-30°)*cos(a) - sin(a)*cos(30°) - sin(30°)*cos(a)

Now remember that:

sin(-x) = -sin(x)

and

cos(-x) = cos(x)

Then we can rewrite our expression as:

sin(a)*cos(30°) - sin(30°)*cos(a) - sin(a)*cos(30°) - sin(30°)*cos(a)

= -2*sin(30°)*cos(a)

and sin(30°) = 0.5

Then:

-2*sin(30°)*cos(a) = -2*0.5*cos(a) = -cos(a)

So we get:

sin(a-30)-sin(a+30)= - cos(a)

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$\begin{gathered} \text{diameter,d}=2\times radius,r \\ d=2r \\ r=\frac{d}{2} \\ r=\frac{12m}{2} \\ r=6m \end{gathered}$

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Substituting for r and h in the formula will give

$\begin{gathered} A_{cylinder}=2\pi r^2+2\pi rh \\ r=6m;h=9m;\pi=3.14 \\ A_{cylinder}=2\times3.14\times6^2+2\times3.14\times6\times9_{} \end{gathered}$ $\begin{gathered} A_{cylinder}=6.28\times36+6.28\times54 \\ =226.08+339.12 \\ =565.2m^2 \end{gathered}$

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1 year ago

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Answer:

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Step-by-step explanation:

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3 years ago

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