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3 years ago

Please help me I will crown

Mathematics

2 answers:

Xelga [282]3 years ago

8 0

The answer to this question is C

Naddika [18.5K]3 years ago

3 0

Answer: c

Step-by-step explanation:

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If 180° < α < 270°, cos⁡ α = −817, 270° < β < 360°, and sin⁡ β = −45, what is cos⁡ (α + β)?

eduard

Answer:

$cos(\alpha+\beta)=-\frac{84}{85}$

Step-by-step explanation:

we know that

$cos(\alpha+\beta)=cos(\alpha)*cos(\beta)-sin(\alpha)*sin(\beta)$

Remember the identity

$cos^{2} (x)+sin^2(x)=1$

step 1

Find the value of $sin(\alpha)$

we have that

The angle alpha lie on the III Quadrant

The values of sine and cosine are negative

$cos(\alpha)=-\frac{8}{17}$

Find the value of sine

$cos^{2} (\alpha)+sin^2(\alpha)=1$

substitute

$(-\frac{8}{17})^{2}+sin^2(\alpha)=1$

$sin^2(\alpha)=1-\frac{64}{289}$

$sin^2(\alpha)=\frac{225}{289}$

$sin(\alpha)=-\frac{15}{17}$

step 2

Find the value of $cos(\beta)$

we have that

The angle beta lie on the IV Quadrant

The value of the cosine is positive and the value of the sine is negative

$sin(\beta)=-\frac{4}{5}$

Find the value of cosine

$cos^{2} (\beta)+sin^2(\beta)=1$

substitute

$(-\frac{4}{5})^{2}+cos^2(\beta)=1$

$cos^2(\beta)=1-\frac{16}{25}$

$cos^2(\beta)=\frac{9}{25}$

$cos(\beta)=\frac{3}{5}$

step 3

Find cos⁡ (α + β)

$cos(\alpha+\beta)=cos(\alpha)*cos(\beta)-sin(\alpha)*sin(\beta)$

we have

$cos(\alpha)=-\frac{8}{17}$

$sin(\alpha)=-\frac{15}{17}$

$sin(\beta)=-\frac{4}{5}$

$cos(\beta)=\frac{3}{5}$

substitute

$cos(\alpha+\beta)=-\frac{8}{17}*\frac{3}{5}-(-\frac{15}{17})*(-\frac{4}{5})$

$cos(\alpha+\beta)=-\frac{24}{85}-\frac{60}{85}$

$cos(\alpha+\beta)=-\frac{84}{85}$

4 0

3 years ago

Three numbers are in the ratio 3:9:10. If 10 is added to the last number, then the three numbers form an arithmetic progression.

MrRa [10]

Answer:

 The numbers are 6, 18, and 30 

Step-by-step explanation:

If the three numbers are in the ratio of 3:9:10,

let the numbers be 3x, 9x and 10x.

If 10 is added to the last number to form an arithmetic progression

Then, 3x 9x (10x+10) are the progression

The common difference of an arithmetic progression (d) = T₂ - T₁ = T₃ - T₂

T₂-T₁ = T₃ - T₂ .............. Equation 1

Where T₁ = first term of the progression, T₂ = Second term of the progression, T₃ = third term of the progression

Given: T₁ = 3x, T₂ = 9x, T₃ = 10x +10

Substituting these values into equation 1

9x-3x = (10x+10)-9x

Solving the equation above,

3x = 10+x

3x-x = 10

2x = 10

x = 10/2

x = 2.

Therefore the numbers are 6, 18, and 30 

7 0

3 years ago

Solve. You must factor first. 2n^2 +9n - 35=0

Ksivusya [100]

Answer:

Step-by-step explanation:

2n² + 9n - 35 = (2n-5)(n+7)

n = 2.5, -7

7 0

3 years ago

Read 2 more answers

If a^20=(a^n)^m what are the values for m and n

Alinara [238K]

N = 2 and m=10. You multiply them

7 0

3 years ago

If <5 is 63 degrees find the measure of <3.

Hatshy [7]

<5 = <1 = <4 = <8 = 63

Straight line = 180

180 - 63 = 117

<3 = 117

6 0

3 years ago