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Sedaia [141]
3 years ago
6

I need help with this question pleas e

Mathematics
1 answer:
ollegr [7]3 years ago
4 0

Answer:

B

Step-by-step explanation:

The double angle formulae for cosine is

cos2x = cos²x - sin²x

[ using sin²x + cos²x = 1 ]

cos2x = cos²x - (1 - cos²x) = cos²x - 1 + cos²x = 2cos²x - 1

Also cos2x = (1 - sin²x) - sin²x = 1 - sin²x - sin²x = 1 - 2sin²x

The double angle formulae are

cos2x = cos²x - sin²x = 2cos² - 1 = 1 - 2sin²x

Hence

cos60° = cos²30° - sin²30°

cos60° = 2cos²30° - 1

cos60° = 1 - 2sin²30°

B is not a representation of cos60°

         

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Answer:

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Yesterday morning at 8 a.m. the temperature was -14˚F. At noon it was 10 degrees warmer. The temperature increase between noon a
OLEGan [10]
The temperature was -14°F at 8 a.m.

At noon is was 10 degrees warmer - the temperature increase was 10°F
-14°F + 10°F = -4°F

The tempertaure increase between noon and 4 p.m. was twice the previous increase in temperature, which was 10°F.
10°F x 2 = 20°F

We want to know the temperature at 4 p.m. so we just add it up to the previous result.
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SOMEONE HELP PLEASE! ASAP!
Luba_88 [7]
When two lines intersect, the angles across from the intersection (the "X") are congruent (equal), and referred to as "vertical angles."
So by the rule of vertical angles are congruent, we can set them equal:
{x}^{2}  - 6x = 1\div2 \: x + 42 \\  {x}^{2}  - 6x - 1 \div 2 \: x = 42 \\  {x}^{2}  - 6.5x = 42
{x}^{2}  - 6.5x - 42 = 0 \\ multiply \: both\: sides \: by \: 2 \: to \: get \\ rid \: of \: the \: decimal \\ 2({x}^{2}  - 6.5x - 42) = 2(0)
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to factor we need the factors of 84:
1×84, 2×42, 3×28, 4×21, 6×14
Now we need one of those factors ×2 ( from the x^2 term) minus the other factor to equal 13 (the middle term)
it turns out that if we use 4×21: 4×2 = 8
and 21-8 = 13. Woohoo! we got it
So now we have:
2 {x}^{2}  - 13x - 84 = 0 \\ (2x - 21)(x + 4) = 0
Now set each factor = 0
1) 2x - 21 = 0 and 2) x + 4 = 0
1) 2x - 21 = 0, 2x = 21, x = 21/2 = 10.5
2) x + 4 = 0, x = -4

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1) x = 10.5
{x}^{2}  - 6x =  {(10.5)}^{2}  - 6(10.5) \\  = 110.25 - 63 = 47.25
1/2x + 42 = 1/2(10.5) + 42 = 5.25 + 42 = 47.25
47.25 = 47.25
BAM SO IT LOOKS LIKE THAT'S IT!!
But let's check 2) first:
2) x = -4
{( - 4)}^{2}  - 6( - 4) = 16 + 24 = 40
1/2x + 42 = 1/2(-4) + 42 = -2 + 42 = 40
40 = 40, so both work!!
But it asks for m<1, and <1 is supplementary because it lies on same line, meaning the sum of both = 189
Therefore m<1 = 180 - 47.25 = 132.75°
OR m<1 = 180 - 40 = 140°


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