The cosine function is an even function, which means that for every point $(x,y)$ on the graph of $y=cos(x)$ then the point $(-x,y)$ also lies on the graph of the function. In other words, we can write:

$cos(-170^{\circ})=cos(170^{\circ})$

But:

$170^{\circ}=180^{\circ}-10^{\circ}$

So:

$cos(170^{\circ})=cos(180^{\circ}-10^{\circ})$

By property:

$cos(a-b)=cosacosb+sinasinb \\ \\ a=180^{\circ} \\ \\ b=10^{\circ} \\ \\ cos(170^{\circ} )=cos(180^{\circ} -10^{\circ})=cos180^{\circ} cos10^{\circ} +sin180^{\circ} sin10^{\circ} \\ \\ cos(170^{\circ})=-cos(10^{\circ})+0 \\ \\ \boxed{cos(170^{\circ})=-cos(10^{\circ})}$

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Trigonometric functions: brainly.com/question/2680050

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4 0

3 years ago

6,10,14 ... Find the 30th term.

andriy [413]

Answer:

Step-by-step explanation:

$a_n=a_1+d(n-1)\\\\\\10-6=4 \ \ and\ \ 14-10=4\quad\implies\qquad d=4\\\\a_1=6\\\\\\a_{30}=6+4(30-1)=122$

7 0

2 years ago

1/3x-137.45=252.60 what is the value of x

nikdorinn [45]

The value of x is 1170.15 because first you add 137.45 from both sides of the equation, then your new equation should be 1/3x=390.05. After that you use the keep change flip method to help you divide 390.05 by 1/3 which will be 390.05 times 3 divided by 1 and your final answer should be x=1170.15 or 1170.15

7 0

3 years ago

Which is the value of 10 x 5(2/5)x 4(1/3)?

Molodets [167]

Answer:

26 2/3

Step-by-step explanation:

4 0

3 years ago

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