cos 255=cos(210+45)=(cos210*cos45-sin210*sin45) cos 210º=cos 30º=-√3/2 in quadrant III where cos is negative sin 210º=sin 30º=-1/2 in quadrant III where sin is also negative

2015年4月25日 · cos 255 deg = cos (180 + 75) = (-1)cos 75 - 0 = -0.26 cos 255 deg = -0.26. Answer link. Related questions.

2016年8月2日 · Use the trig identity; #2cos^2 a = 1 + cos 2a# If a = 255 --> 2a = 510 --> cos 2a = cos 510 = cos (150 + 360) = cos 150 = # - sqrt3/2#

Question 869667: Using sum or difference formulas, find the exact value of cos(105∘). Express your answer in the form cos(105degrees)=a√(1−√b)/4 for some numbers a and b. Express …

2015年9月8日 · How do you find the exact functional value sin (-255 degrees) using the cosine sum or difference identity? Trigonometry Trigonometric Identities and Equations Sum and …

2018年3月27日 · sin 255 = sin (75 + 180) = - sin 75. Find sin 75 by using the trig identity: sin (a + b) = sin a.cos b + sin b.cos a

Here is an example of using a sum identity: Find #sin15^@#.. If we can find (think of) two angles #A# and #B# whose sum or whose difference is 15, and whose sine and cosine we know.

#sqrt17[cos(255.96375653207^@)+i sin (255.96375653207^@)]# Explanation: First we add the complex numbers

2016年7月8日 · 6.15549 cos 17pi/12 = cos 255=-0.2588 sin 17pi/12= sin 255 =-0.9659 In cartesean coordinates the first point would be (3 cos 17pi/12, 3 sin 17pi/12) Or,(-0.77645, …

2015年4月25日 · Use the trig identity: cos (a + b) = cos a*cos b - sin a*sin b. cos 195^circ = cos (180 + 15) = cos 180*cos 15 - sin 180* sin 15 = (-1)*(sqrt3)/2 - 0 = -(sqrt3)/2 cos 195^circ = - …