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1. ### why is 22/7 used for pi?

...fraction with a denominator under 106! That makes 22/7 a particularly good approximation to pi for such a small denominator.... It has been known and used since antiquity to approximate pi in rational calculations...

5 Answers · Science & Mathematics · 12/07/2013

2. ### Express the tan(22.5degrees) using the cos(45degrees). Simplify radicals to lowest form without calculator?

...case, since 22.5 is half of 45, you just set x = 45 degrees then tan(22.5) becomes tan(45/2) Using the formula, it becomes tan(45/2) = [1 - cos(45)] / sin(45) It just so...

2 Answers · Science & Mathematics · 14/07/2012

3. ### How do you solve 7^x=22 using logarithms?

here's the rule you need: log(m^n) = n · log(m) log(7^x) =log(22) -> x · log(7) = log(22) x · log(7)/log(7) = log(22)/log(7) x = log(22)/log(7)

3 Answers · Science & Mathematics · 28/03/2013

4. ### How do you find sin(-22.5) using a half-angle identity?

sin(-22.5) =-sin(22.5) Using the half-angle identity sin^2(22.5) = (1-cos(45))/2 = (1-(1/sqrt(2)))/2 = (sqrt(2)-1)/2sqrt(2) = (2-sqrt(2))/4 => sin(-22.5) = -(1/2)sqrt(2-sqrt(2))

1 Answers · Science & Mathematics · 04/11/2008

5. ### Simplify cos 22.5 using trigonometric identities?

cos2A = 2cos²A - 1 => cos45 = 2cos²(22.5) - 1 => √2/2 = 2cos²(22.5) - 1 => cos²(22.5) = (√2/2 + 1)/2 i.e. cos²22.5 = √2/4 + 1/2 => (√2 + 2)/4 so, cos22.5 = √(√2 + 2)/2 :)>

3 Answers · Science & Mathematics · 05/07/2013

6. ### How to construct line segment with length sin(pi/22) only using compass and ruler?

Assume that you have a segment of length 1 and a segment of length sin(pi/22). You could use these to construct an angle of pi/22, which would be the exterior angle of a 44-gon...

2 Answers · Science & Mathematics · 11/02/2015

7. ### how to solve 9x-4y=26 AND 18x+7y=22 using linear system of Elimination?

9x - 4y = 26 18x + 7y = 22 By elimination method, multiply the first equation by -2 and solve for y...

1 Answers · Science & Mathematics · 01/03/2011

8. ### Find the exact value of tan 22.5 by using the expression for tan 2x?

...and Tan 45° = Tan (2*22.5°) Therefore 1 = Tan (2*22.5°). Using the double angle formula for tangent, which is Tan 2x = (2Tanx)/(1...

2 Answers · Science & Mathematics · 11/04/2016

9. ### Solve the equation (6x-17)^2=22 using square root method and use your calculator to find the smallest solution?

(6x-17)^2=22 36x^2 - 102x - 102x +289 = 22 36x^2 -204x -267 - 0 x = { 204 +/- sqrt[(-204)^2 - 4(36)(-267)] } / 2(36) = {204 +/- sqrt(41616 - 38448)} / 72 = {204 +/- 56.285} / 72 = 3.615 or 2.052 abswer ----> C)2.05 is one of the possible answers

2 Answers · Science & Mathematics · 08/04/2012