1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Tatiana [17]
3 years ago
7

Provethat2 cos (A +45°) cos (B-45°) = cos 2A​

Mathematics
1 answer:
wolverine [178]3 years ago
6 0

Answer:

Step-by-step explanation:

2 cos(A+45)cos (B-45)

=2[cos A cos 45-sin A sin 45][cos B cos 45+sin B sin 45]

=2[cos A ×1/√2-sin A ×1/√2][cos B×1/√2+sin B×1/√2]

=2[1/√2(cos A-sin A)][1/√2(cos B-sin B]

=2×1/√2×1/√2 (cos A-sin A)(cos B+sin B)

=cosA cos B+cos A sin B-sin A cos B-sin A sin B

=cos A cos B-sin A sin B-(sin A cos B-cos A sin B)

=cos (A+B)-sin (A-B)

i think there should be A in place of B.

then

=cos (A+A)-sin (A-A)

=cos 2A-sin 0

=cos 2A

as sin 0=0

You might be interested in
Calculate to the nearest 1/10th meter the length of the side of a 7th, 12th, and 30th hectare square plot.
Tems11 [23]

Answer and explanation:

To find : Calculate to the nearest 1/10th meter the length of the side of a 7th, 12th, and 30th hectare square plot.

Solution :

The area of the square is given by,

A=s^2 where s is the side length.

We know,  1 \text{ hectare}=10,000\ m^2

1) The area of square plot is 7 hectare.

Area in meter square is A=7\times 10000=70000\ m^2

Substitute the value in the formula,

70000=s^2

\sqrt{70000}=s

264.57=s

Side nearest to 1/10th meter is 264.8 meter.

2) The area of square plot is 12 hectare.

Area in meter square is A=12\times 10000=120000\ m^2

Substitute the value in the formula,

120000=s^2

\sqrt{120000}=s

346.41=s

Side nearest to 1/10th meter is 346.4 meter.

3) The area of square plot is 30 hectare.

Area in meter square is A=30\times 10000=300000\ m^2

Substitute the value in the formula,

300000=s^2

\sqrt{300000}=s

547.72=s

Side nearest to 1/10th meter is 547.7 meter.

5 0
2 years ago
Martha was recarpeting her bedroom, which was 15 feet long and 10 feet wide. How many square feet (the area) will she need to pu
Veseljchak [2.6K]

Answer:

150 Square feet

Step-by-step explanation:

15 feet long

10 feet wide

Area = length x width

15 x 10 = 150

150 Square feet

Hope this helped!

3 0
2 years ago
What is the measure compliment for 57 degrees
puteri [66]
To find this, simply subtract 57 from 90. 90 is the measurement for a completed compliment equation, and 57 is the part of the compliment we know.

33 is the answer
7 0
3 years ago
Two sides of a triangle measure 8 and 13. what represents x, the possible length in inches of the remaining side
Liula [17]

Answer:

the  possible number would be 159 in

Step-by-step explanation:

8 0
2 years ago
You can pay $4.80 for 8 pounds of sugar or $11.75 for 25 pounds of
cricket20 [7]
25 pounds would be a better deal
7 0
2 years ago
Read 2 more answers
Other questions:
  • Armando read 20 pages of his 200-page book in 4 hours. At this rate, how long will it take him to read the entire book?
    8·1 answer
  • How can you use distance and slope formulas to classify quadrilaterals?
    14·2 answers
  • If you roll a number cube 54 times, about how many times do you expect to roll a number less than 5?
    12·1 answer
  • Help please............
    6·1 answer
  • In what ways is it useful to develop an algorithm for adding and subtracting rational numbers?
    13·2 answers
  • How is this ejercice: 15+x=4
    5·1 answer
  • Hello there are 4 questions in this it will look like a lot but it is not and you don't have to answer all of it just look at th
    14·1 answer
  • PLEASE SOMEONE HELP ASAP
    8·1 answer
  • If a x b = 2a - 3b + ab, then 3 x 5 + 5 x 3 is equal to?
    13·1 answer
  • Two angles of a triangle are 40 and 80 digress. Find the third angle.
    10·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!