$MathMaster logo$

MathMaster

Home
general
given cos26 k find cos13

Question

given cos26=k find cos13

93

likes

465 views

Answer to a math question given cos26=k find cos13

$Expert avatar$

4.9

114 Answers

cos(2θ) = 2 \times cos^2(θ) - 1

cos^2(θ) = \frac{(cos(2θ) +1)}{2}

cos^2(13) = \frac {cos(26) +1}{2}

cos^2(13) = \frac{k +1}{2}

\cos\:13\:=\pm\sqrt{\left(\frac{k+1}{2}\right)}}

Frequently asked questions (FAQs)

Math question: For a triangle with side lengths of 5 cm, 8 cm, and 10 cm, what is its area using Heron’s Formula?

+

What is the derivative of f(x) = x^3 - 2x^2 + 5x - 8?

+

What is the limit as x approaches infinity of (e^x - x)/(x^2)?

+

New questions in Mathematics

A person who weighs 200 pounds on earth would weigh about 32 pounds on the moon. Find the weight of a person on earth who would weigh 15 pounds on the moon.

Revenue Maximization: A company sells products at a price of $50 per unit. The demand function is p = 100 - q, where p is the price and q is the quantity sold. How many units should they sell to maximize revenue?

The sum of two numbers is 6, and the sum of their squares is 28. Find these numbers exactly

In a store, a person carries 14 kilos of rice and 28 kilos of flour. In what ratio are the kilos found? (Remember to simplify until you reach an irreducible fraction)

Clara usually walks briskly to the farmers' market and it takes her 22 minutes. Today she walked leisurely and it took 61/2 minutes. How much more time than usual did she take to reach the market today?

If 0101, what is the binary representation of the 4x16 decoder output?

reduce the expression (7.5x 12)÷0.3

At the dance there are 150 boys the rest are girls. If 65% are girls what is the total amount in the room

A tree cast a shadow of 26 meters when the angle of evaluation of the sum is 24°. Find the height of the tree to the nearest meter

Read the “Local Communities as Stakeholders: Does Amazon Really Need Tax Breaks?” example on p. 83 in Ch. 3 of Management: A Practical Introduction. In your response, discuss whether you feel that tax breaks for big companies benefit local communities. Describe ways to attract business to a region without having a negative impact on the larger community.

To verify that a 1 kg gold bar is actually made of pure gold, a dynamometer is used to record the weight of the bar submerged in water and out of water. a) What would be the value of the weight of the ingot recorded by the dynamometer out of the water? b) What magnitude of thrust does the ingot receive when it is submerged? c) What would the weight of the ingot have to be when it is submerged? Data Pagua = 1000 kg/m³ Pagua= 19300 kg/m³

Determine the general solution of the equation y′+y=e−x .

Today a father deposits $12,500 in a bank that pays 8% annual interest. Additionally, make annual contributions due of $2,000 annually for 3 years. The fund is for your son to receive an annuity and pay for his studies for 5 years. If the child starts college after 4 years, how much is the value of the annuity? solve how well it is for an exam

9n + 7(-8 + 4k) use k=2 and n=3

If the area of a circle is 75.7ft2, what is the radius? Give the answer in metres. Round answer to 2 decimal places and enter the units.