A cylinder has a radius of (2−1) cm(\sqrt{2}-1)\text{ cm} and a volume of (12+32)π cm3(12+3\sqrt{2})\pi\text{ cm}^3. Find, without using a calculator, the exact value of its height, h cmh\text{ cm}, in the form a+b2a+b\sqrt{2}, where aa and bb are integers.

Work through it with AI →

It won't just hand you the answer — it asks where you're stuck.How the checker works

Worked solution

1

1. Set up the equation for the volume of the cylinder

Volume of cylinder, V=πr2hV = \pi r^2 h
(12+32)π=π(2−1)2h(12+3\sqrt{2})\pi = \pi (\sqrt{2}-1)^2 h

2. Expand the squared term and make $h$ the subject

12+32=(2−22+1)h12+3\sqrt{2} = (2 - 2\sqrt{2} + 1) h
12+32=(3−22)h12+3\sqrt{2} = (3 - 2\sqrt{2}) h
h=12+323−22h = \frac{12+3\sqrt{2}}{3-2\sqrt{2}}

3. Rationalise the denominator to find $h$ in the required form

h=12+323−22×3+223+22h = \frac{12+3\sqrt{2}}{3-2\sqrt{2}} \times \frac{3+2\sqrt{2}}{3+2\sqrt{2}}
h=36+242+92+6(2)32−(22)2h = \frac{36 + 24\sqrt{2} + 9\sqrt{2} + 6(2)}{3^2 - (2\sqrt{2})^2}
h=36+332+129−8h = \frac{36 + 33\sqrt{2} + 12}{9 - 8}
h=48+332h = 48 + 33\sqrt{2}

Answer

48+33248 + 33\sqrt{2}

AI analysis — may contain mistakes.

Worked this one out on paper? Snap your steps and Gigle's AI math checker will circle the step where it went wrong.

More questions on this topic

  1. 1下列式子中,是最简二次根式的是( ). A. 4 \sqrt[]{4} B. 6 \sqrt[]{6} C. 8 \sqrt[]{8} D. 12 \sqrt[]{12}
  2. 2The diagram shows a prism in which its cross-section is a regular hexagon of side (5+3)(5 + \sqrt{3}) cm. Find an expressio…
  3. 3The triangle ABC is such that its area is 16+7102 cm2\dfrac{16 + 7\sqrt{10}}{2}\ \text{cm}^2, the length of AB is (32+5) cm(3\sqrt{2} + \sqrt{5})\ \text{cm}…
  4. 4Given that sin⁡A=−35\sin A = -\frac{3}{5} and cos⁡B=−817\cos B = -\frac{8}{17}, where angle AA and angle BB are in the same quadrant,…
  5. 5In ΔABC\Delta ABC, AC=12 cmAC = 12\text{ cm}, ∠ABC\angle ABC is a right angle, ∠ACB=π6\angle ACB = \frac{\pi}{6} radians and MM is the…