2018年3月27日 · Use the half angle formula: #tan (a/2) = (1 - cos a)/sin a# In this case --> #tan (a/2) = tan 15#--> #cos a = cos 30 = sqrt3/2#

2015年8月30日 · color(red)(cos15 = sqrt(2 +sqrt3)/2) > The cosine half-angle formula is cos(x/2) = ±sqrt((1 + cos x) / 2) The sign is positive if x/2 is in the first or fourth quadrant and negative if x/2 is in the second or third quadrant. 15° is in the first quadrant, so the sign is positive. 15= 30/2 ∴ cos15 = cos(30/2) = sqrt((1+cos30)/2) cos15 = sqrt((1 + sqrt3/2)/2) = sqrt((2 + sqrt3)/4) cos15 ...

2017年2月8日 · a_n = 1/2n(n+1) These are recognisable as triangular numbers, but let's use a general method for finding matching polynomial formulas...

2016年12月13日 · Please see the explanation. Compute the dot-product: baru*barv = 3(-1) + 15(5) = 72 The two vectors are not orthogonal; we know this, because orthogonal vectors have a dot-product that is equal to zero. Determine whether the two vectors are parallel by finding the angle between them.

2016年1月11日 · 24 The exterior angles of a polygon always add up to 360 degrees. Given this a regular polygon, all the angles are equal and all the sides are equal. The number of sides is therefore 360/15 = 24

2016年2月8日 · i^15 = -i Remember that i^2 = -1. Thus, i^4 = (i^2)^2 = (-1)^2 = 1 Also, remember the power rule a^m * a^n = a^(m+n) Thus, you have i^15 = i^(4 + 4 + 4 + 3) = i^4 * i^4 * i^4 * i^3 = 1 * 1 * 1 * i^3 = i^3 = i^2 * i = -1 * i = -i =========== Also, I'd like to offer you a more general solution for i^n, with n being any positive integer. Try to recognize the pattern: i = i i^2 = …

2014年11月5日 · Examples x is at least 2. <=> x ge 2 x is no more than 5. <=> x le 5 I hope that this was helpful.

2015年11月10日 · To find a pattern in this sequence, first write out the original sequence: (i) #color(blue)(2),5,10,17,26# Then write out the sequence of differences between successive terms of that sequence:

2016年7月12日 · An exclamation point denotes something called a factorial. The formal definition of n! (n factorial) is the product of all the natural numbers less than or equal to n. In math symbols: n! = n*(n-1)*(n-2)... Trust me, it's less confusing than it sounds. Say you wanted to find 5!. You just multiply all the numbers less than or equal to 5 until you get to …

2014年3月21日 · The acceptability of a percent error depends on the application. > In some cases, the measurement may be so difficult that a 10 % error or even higher may be acceptable.