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prisoha [69]
2 years ago
5

3 Prove thatcos130°+cos 110+ cos10=0​

Mathematics
1 answer:
Evgesh-ka [11]2 years ago
5 0

We know, cos A + cos B = 2cos(C+D)/2 × cos(C - D)/2

So,

cos 130 + cos 110 + cos 10

cos 130 + 2cos (110+10)/2 × cos( 110-10)/2

cos 130 + 2cos 60 × cos 50

cos ( 180 - 50 ) + 2cos60 cos 50

We know, cos ( 180 - A ) = -cos A

2cos 60 cos 50 - cos 50

Also, cos 60 = 0.5

2×0.5 cos 50 - cos50

cos 50 - cos 50

0  = RHS.

Hence proved

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Kipish [7]

Answer:

There are no solutions.

D) no solution

7 0
2 years ago
Please help!! Math problem and I don't know how to do it!! 14 points!!
IgorLugansk [536]

Let Brian's steps have a measure of 1, and Richard's steps have a measure of k. Then after each walks 5 steps away from the other, their distance apart is

... 5 + 5k

We are told that distance is equal to 9 of Richard's steps, so is equal to 9k.

... 5 + 5k = 9k

... 5 = 4k . . . . . . . subtract 5k

... 5/4 = k . . . . . . divide by 4

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6 0
2 years ago
Help with this pleaseeee​
ELEN [110]

Answer:

(- 3, 37) and (- \frac{5}{2}, \frac{63}{2} )

Step-by-step explanation:

Given the 2 equations

2x² - y + 19 = 0 → (1)

y + 11x = 4 → (2) ← subtract 11x from both sides

y = 4 - 11x → (3)

Substitute y = 4 - 11x into (1)

2x² - (4 - 11x) + 19 = 0

2x² - 4 + 11x + 19 = 0

2x² + 11x + 15 = 0 ← in standard form

(2x + 5)(x + 3) = 0 ← in factored form

Equate each factor to zero and solve for x

2x + 5 = 0 ⇒ 2x = - 5 ⇒ x = - \frac{5}{2}

x + 3 = 0 ⇒ x = - 3

Substitute these values into (3) for corresponding values of y

x = - \frac{5}{2} : y = 4 + \frac{55}{2} = \frac{63}{2} ⇒ (- \frac{5}{2}, \frac{63}{2} )

x = - 3 : y = 4 + 33 = 37 ⇒ (- 3, 37 )

4 0
2 years ago
Students are planning a 3-day hiking trip in the mountains. The hike covers a distance of 18.5 kilometers. The students hike 0.2
Iteru [2.4K]
9.11 kilometers
18.5 - 0.28 = 18.22
18.22 / 2 = 9.11
7 0
3 years ago
PLEASE HELP!<br>(I know its not math, stop hatin!)<br>(If a human and a dog were the same)
Vaselesa [24]

Answer:

1st one

Step-by-step explanation

I have NEVER in my life seen a dog with pants on its back legs, only on both so yeah.

4 0
3 years ago
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