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The formula for the surface area of a cylinder is:
2<span>π</span><span>r</span><span>h </span><span>+ </span><span>2</span><span>π</span><span>r^</span><span>2
If we substitute in the measurements that we know, you get:
2</span><span>
(3.5) (14) + 2</span><span> (3.5)^2
If we simplify this expression, we get:
98</span><span> + 24.5</span><span>
If you simplify once more, you get
122.5</span><span> or </span><span>≈ 384.85
Therefore, the surface area is 122.5</span> or about 384.85<span>
</span>
2<span>π</span><span>r</span><span>h </span><span>+ </span><span>2</span><span>π</span><span>r^</span><span>2
If we substitute in the measurements that we know, you get:
2</span><span>
If we simplify this expression, we get:
98</span><span>
If you simplify once more, you get
122.5</span><span>
Therefore, the surface area is 122.5</span>
</span>
X = 18°
cos 54° = sin 36°
cos 3 x = sin 2 x
cos ( 2 x + x ) = sin 2 x
cos 2 x cos x - sin 2 x sin x = 2 sin x cos x
( cos² x - sin² x ) cos x - 2 sin² x cos x = 2 sin x cos x / : cos x
( divide both sides by cos x )
cos² x - sin² x - 2 sin² x = 2 sin x
1 - sin² x - 3 sin² x - 2 sin x = 0
- 4 sin² x - 2 sin x + 1 = 0 substitution: u = sin x
- 4 u² - 2 u + 1 = 0
u = 2 -√20 / - 4 sin 18° = (√ 5 - 1 )/4
cos 18° = √( 1² - ((√5 - 1)/4)²
cos 18° = (10+2√5)^(1/2) / 4
cos 54° = sin 36°
cos 3 x = sin 2 x
cos ( 2 x + x ) = sin 2 x
cos 2 x cos x - sin 2 x sin x = 2 sin x cos x
( cos² x - sin² x ) cos x - 2 sin² x cos x = 2 sin x cos x / : cos x
( divide both sides by cos x )
cos² x - sin² x - 2 sin² x = 2 sin x
1 - sin² x - 3 sin² x - 2 sin x = 0
- 4 sin² x - 2 sin x + 1 = 0 substitution: u = sin x
- 4 u² - 2 u + 1 = 0
u = 2 -√20 / - 4 sin 18° = (√ 5 - 1 )/4
cos 18° = √( 1² - ((√5 - 1)/4)²
cos 18° = (10+2√5)^(1/2) / 4