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3 years ago

Cos s=-2/5 and sin t=4/5, s and t are in quadrant II find cos(s+t) and cos(s-t)

Mathematics

1 answer:

mojhsa [17]3 years ago

5 0

Answer:

•cos(s+t) = cos(s)cos(t) - sin(s)sin(t) = (-⅖).(-⅗) - (√21 /5).(⅘) = +6/25 - 4√21 /25 = (6-4√21)/25

•cos(s-t) = cos(s)cos(t) + sin(s)sin(t) = (-⅖).(-⅗) + (√21 /5).(⅘) = +6/25 + 4√21 /25 = (6+4√21)/25

cos(t) = ±√(1 - sin²(t)) → -√(1 - sin²(t)) = -√(1 - (⅘)²) = -⅗

sin(s) = ±√(1 - cos²(s)) → +√(1- cos²(s)) = +√(1 - (-⅖)²) = √21 /5

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Answer:

C. 225°.

Step-by-step explanation:

1) according to the condition minor arc is 135°;

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Mademuasel [1]

Answer:

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Step-by-step explanation:

Given:

During a sale, a store offered a 20% discount on a TV that originally sold for $710. After the sale, the discounted price of the TV was marked up by 20%

To Find:

What was the price of the TV after the markup? Round to the nearest cent.

Solution:

$710 × (1 + 20%) × (1 - 20%)

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1 year ago

Describe and correct the error a student made in finding the midpoint cd with c(-4,5) and d(-1,-4).

Gnesinka [82]

Answer:

Step-by-step explanation:

The formula for finding the midpoint of two coordinates is expressed as;

M(X,Y) = $(\frac{x_1+x_2}{2} , \frac{y_1+y_2}{2})$

Given the coordinates c(-4,5) and d(-1,-4), x1 = -4, y1 = 5, x2 = -1 and y2 = -4.

For the X coordinate of the midpoint

X = x1+x2/2

X = -4+(-1)/2

X = -4-1/2

X = -5/2

X = -2.5

Similarly for Y:

Y = y1+y2/2

Y = 5+(-4)/2

Y = 5-4/2

Y = 1/2

Y = 0.5

Hence the midpoint coordinate of C(-4,5) and D (-1,-4) is (-2.5, 0.5)

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