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2 years ago

What is the proof the formula for cos(A+B)=cosAcosB-sinAsinB?

1 answer:

8 0

Given data, cos(A - B) = cosAcosB + sinAsinB
let, A=60' and B=30' ( here the ' sign bears degree) 
L.H.S = cos(A - B) 
=cos (60'-30) ( using value of A and B ) 
=cos30' 
= sqrt3/2 
R.H.S= cosAcosB + sinAsinB 
=cos60' cos30' + sin60' sin30' 
= 1/2* sqrt3/2+ sqrt3/2*1/2 
= sqrt3/4 + sqrt3/4 
=2 sqrt3/4 
= sqrt3/2 
so L.H.S =R.H.S or cos(A - B) = cosAcosB + sinAsinB

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Please help! Tim and Jane both work at a company that sells boxes of breakfast cereal. The boxes of cereal cost £3.00 and the am

patriot [66]

Answer: Jane needs to reduce the price by 20%

Step-by-step explanation: The first thing to note is the original price of the cereal and that is given as £3 for every 160 grams.

The change proposed by Tim is as follows;

Put 25% more cereal in the box (and do not change the price). That means 160 g plus 25%. Mathematically, this can be expressed as;

New weight = 160 + (160 * 25%)

New weight = 160 + (160 * 0.25)

New weight = 160 + 40

New weight = 200

Hence, Tim's idea would result in a cereal box with 200 grams that still cost £3. At this rate, each gram would cost

1 gram = Price / Total grams

1 gram = 3/200

1 gram = 0.015

However, Jane has proposed that the amount of cereal in the box should not be changed, which means the box of cereals should remain 160 grams. The price should be reduced to give the same value as Tim's idea. This means 160 g of cereals should now sell for £0.015 per gram. That would bring the price of 160 g to,

1 gram = 0.015

160 grams = 0.015 * 160

160 grams = 2.4

With Jane's proposal, a 160 g box of cereal should now be sold at £2.4 each. That is a reduction of £0.6

Therefore, the percentage reduction can be calculated as follows;

% decrease = (0.6/3) * 100

% decrease = (1/5) * 100

% decrease = 20

From the results above, Jane should reduce the price (£3 per 160 g) by 20%.

7 0

2 years ago

A clinical test on humans of a new drug is normally done in three phases. Phase I is conducted with a relatively small number of

navik [9.2K]

Answer:

A clinical test on humans of a new drug is normally done in three phases. Phase I is conducted with a relatively small number of healthy volunteers. For example, a phase I test of a specific drug involved only 7 subjects.

Step-by-step explanation:

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2 years ago

mariarad [96]

Answer:

Insurance will pay $250,000 and Ronaldo will pay $90,000

Step-by-step explanation:

50/250 means 50 is the maxi9$50,000 per person for body injury liability while 250 means $250,000 maximum for one accident for body injury liability claim.

18 children each was awarded $20,000 as a result of lawsuit

Total amount of lawsuit=18×$20000= $360000

Ronald has 50/250 BI

Total amount insurance will pay =250,000

Ronald will have to pay= $(360,000-250000)=$90,000

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2 years ago

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damaskus [11]

I hope this helps ;)

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2 years ago

a lunch stand makes a $.75 profit on each chef's salad and $1.20 profit on each caesar salad. On a typical weekday, it sells bet

tangare [24]

Answer:

50 Chef's salads and 50 Caesar salads should be prepared in order to maximize profit.

Step-by-step explanation:

Suppose, the number of Chef's salad is $x$ and the number of Caesar salad is $y$

On a typical weekday, it sells between 40 and 60 Chefs salads and between 35 and 50 Caesar salads.

So, the two constraints are: $40\leq x\leq 60$ and $35\leq y\leq 50$

The total number sold has never exceed 100 salads. So, another constraint will be: $x+y\leq 100$

According to the graph of the constraints, the vertices of the common shaded region are: $(40,35), (60,35), (60,40), (50,50)$ and $(40,50)$ (Refer to the attached image for the graph)