![]() |
|
Elementary Math Fractions, Percentages, Word Problems, Equations, Inequations, Factorization, Expansion |
![]() |
| LinkBack | Thread Tools | Display Modes |
February 27th, 2017, 10:47 AM | #1 |
Newbie Joined: Feb 2017 From: uk Posts: 6 Thanks: 0 | Height and area of a triangle - surd
Hey, How do I work out the height of an isosceles triangle as a surd? I have the base length and the length of the side. Then how do I work out the area of a triangle as a surd? Thanks for any help. Last edited by skipjack; February 28th, 2017 at 08:04 AM. |
![]() |
February 27th, 2017, 10:59 AM | #2 |
Math Team Joined: Jul 2011 From: Texas Posts: 2,818 Thanks: 1463 |
$h$ = triangle height $s$ = side length $b$ = base length $h^2 = s^2 - \left(\dfrac{b}{2}\right)^2 \implies h = \sqrt{s^2 - \left(\dfrac{b}{2}\right)^2}$ |
![]() |
February 27th, 2017, 11:06 AM | #3 |
Newbie Joined: Feb 2017 From: uk Posts: 6 Thanks: 0 |
so if my base was 20cm and my side was 30cm. height (2) = 30(2) - (20/2) (2) height (2) = 900 - 100 sorry I'm really bad at this. |
![]() |
February 27th, 2017, 11:16 AM | #4 |
Math Team Joined: Jul 2011 From: Texas Posts: 2,818 Thanks: 1463 |
$h = \sqrt{30^2 - \left(\dfrac{20}{2}\right)^2}$ $h = \sqrt{900 - 100}$ $h = \sqrt{800} = \sqrt{400} \cdot \sqrt{2} = 20\sqrt{2}$ |
![]() |
February 27th, 2017, 11:25 AM | #5 |
Newbie Joined: Feb 2017 From: uk Posts: 6 Thanks: 0 |
Thank you! So the area of the triangle will be 282.8? How do I convert that to a surd? |
![]() |
February 27th, 2017, 02:29 PM | #6 | |
Math Team Joined: Jul 2011 From: Texas Posts: 2,818 Thanks: 1463 | Quote:
$A = \dfrac{1}{2} \cdot b \cdot h$ $A = \dfrac{1}{2} \cdot 20 \cdot 20\sqrt{2} = 10 \cdot 20\sqrt{2} = 200\sqrt{2} \, \,\text{cm}^2$ Last edited by skipjack; February 28th, 2017 at 08:06 AM. | |
![]() |
February 27th, 2017, 02:33 PM | #7 |
Senior Member Joined: Apr 2014 From: Europa Posts: 575 Thanks: 176 | |
![]() |
![]() |
|
Tags |
area, height, surd, triangle |
Search tags for this page |
Click on a term to search for related topics.
|
Thread Tools | |
Display Modes | |
|
![]() | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Calculate area of triangle when height undefined? | DecoratorFawn82 | Geometry | 9 | November 24th, 2014 10:44 PM |
Height unknown but need area. | caters | Algebra | 31 | March 31st, 2014 02:09 PM |
Area of a segment of a circle from % of height. | fishinmyi | Algebra | 6 | October 27th, 2011 10:34 AM |
Height equilateral triangle - formula | e81 | Algebra | 4 | May 18th, 2011 09:41 PM |
Change of triangle height | Valar30 | Calculus | 1 | April 22nd, 2011 12:43 PM |