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3 years ago

Pls help, i need help i dont understand

Mathematics

1 answer:

Svet_ta [14]3 years ago

5 0

Answer:

I think it's 140 not sure

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baherus [9]

Answer: see proof below

Step-by-step explanation:

Given: cos 330 = $\frac{\sqrt3}{2}$

Use the Double-Angle Identity: cos 2A = 2 cos² A - 1

$\text{Scratchwork:}\quad \bigg(\dfrac{\sqrt3 + 2}{2\sqrt2}\bigg)^2 = \dfrac{2\sqrt3 + 4}{8}$

Proof LHS → RHS:

LHS cos 165

Double-Angle: cos (2 · 165) = 2 cos² 165 - 1

⇒ cos 330 = 2 cos² 165 - 1

⇒ 2 cos² 165 = cos 330 + 1

Given: $2 \cos^2 165 = \dfrac{\sqrt3}{2} + 1$

$\rightarrow 2 \cos^2 165 = \dfrac{\sqrt3}{2} + \dfrac{2}{2}$

Divide by 2: $\cos^2 165 = \dfrac{\sqrt3+2}{4}$

$\rightarrow \cos^2 165 = \bigg(\dfrac{2}{2}\bigg)\dfrac{\sqrt3+2}{4}$

$\rightarrow \cos^2 165 = \dfrac{2\sqrt3+4}{8}$

Square root: $\sqrt{\cos^2 165} = \sqrt{\dfrac{4+2\sqrt3}{8}}$

Scratchwork: $\cos^2 165 = \bigg(\dfrac{\sqrt3+1}{2\sqrt2}\bigg)^2$

$\rightarrow \cos 165 = \pm \dfrac{\sqrt3+1}{2\sqrt2}$

Since cos 165 is in the 2nd Quadrant, the sign is NEGATIVE

$\rightarrow \cos 165 = - \dfrac{\sqrt3+1}{2\sqrt2}$

LHS = RHS $\checkmark$

4 0

3 years ago

Does this graph represent a function?

yuradex [85]

Answer:

Yes

Step-by-step explanation:

Graphs are functions when there is only one output for every input. In other words, for every "x" value, there must be only "y" value. This graph depicts a function because it abides by this rule. To be exact, this is an exponential function with the formula: f(x) = (x + 2)².

5 0

2 years ago

A. Graph A B. Graph B C. Graph D. Graph D

igomit [66]

Answer:

Step-by-step explanation:

y = (x-1) (x+4)

when y=0

x=1 and x= -4

so select C

3 0

3 years ago

For a school play,the teacher asked the class to set up the chairs in 20 rows with 25 chairs in each roes after setting up all t

LenKa [72]

500 should be correct

3 0

3 years ago

A bag contains eight yellow marbles, nine green marbles, three purple marbles, and five red marbles. Two marbles are chosen from

lidiya [134]

Answer:

2/15 = 13 1/3 %

Step-by-step explanation:

eight yellow marbles, nine green marbles, three purple marbles, and five red marbles = 25

P(yellow) = yellow/ total =8/25

Keep

7 yellow marbles, nine green marbles, three purple marbles, and five red marbles = 24

P(red) = red/total =5/24

P(yellow then red) = 8/25 * 5/24 = 1/15

Then we have (red, yellow) =

P(red) = red/ total =5/25 = 1/5

Keep

8 yellow marbles, nine green marbles, three purple marbles, and four red marbles = 24

P(yellow) = yellow/total =8/24 = 1/3

P(red, yellow) = 1/5*1/3 = 1/15

Add them together

1/15 + 1/15 = 2/15 =

7 0

3 years ago