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zepelin [54]
3 years ago
8

In aΔABC, if ∠B = 60° and the ratio of two sides is a : c = 2 : √3 + 1, then ∠A= ____.

Mathematics
1 answer:
UkoKoshka [18]3 years ago
4 0

Answer:

∠A= 45°....

Step-by-step explanation:

To find  ∠A first we have to find the length of side B by cosine law:

b^2 = a^2 + c^2 – 2 a c cos B

b^2=(2)^2 +(√3 + 1)^2 - 2(2)(√3 + 1) cos 60

b^2 = 6

Taking square root at both sides:

√b^2 = √6

b= 2.45

Now we can calculate ∠A by sine law:

b / sin B = a / sin A

2.45 / sin 60 = 2 / sin A

sin A= 2* √3/2 /2.45

sin A = 2√3/2 * 1/2.45

sinA = 2√3/ 4.9

sin A = 0.7069

sin A = 0.707

A=45°

Thus ∠A= 45°....

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Question:

The geometric sequence ai is defined by the formula: a₁ = 8, aᵢ = aᵢ₋₁(-1.5 ).

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Answer:

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Step-by-step explanation:

Given

Geometric Sequence

a₁ = 8

aᵢ = aᵢ₋₁(-1.5 )

First, the common ratio needs to be calculated.

The common ratio is the ratio of a term to its previous term.

In other words,

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We can calculate the common ratio from aᵢ = aᵢ₋₁(-1.5 ) by dividing both sides by aᵢ₋₁. This gives

aᵢ / aᵢ₋₁ = aᵢ₋₁(-1.5 ) / aᵢ₋₁

aᵢ / aᵢ₋₁ = -1.5

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Now that we've had the common ratio and first term to be -1.5 and 8 respectively, the sum of 20 terms can then be calculated using the sum of n terms formula.

Sₙ = a(1 - rⁿ)/(1 - r)

We're making use of this formula because r is less than 1

Where n = 20

a = first term = 8

r = -1.5

By substituting these values; we get

S₂₀ = 8(1 - (-1.5)²⁰)/(1 - (-1.5))

S₂₀ = 8(1 - (-1.5)²⁰)/(1 + 1.5))

S₂₀ = 8(1 - (-1.5)²⁰)/(1 + 1.5))

S₂₀ = 8(1 - (3325.25673008

))/(2.5)

S₂₀ = 8(1 - 3325.25673008

)/(2.5)

S₂₀ = 8(-3324.25673008

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S₂₀ = -10,637.621536256

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3 years ago
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Answer:

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