Difference between revisions of "2017 AMC 8 Problems/Problem 6"

(Created page with "==Problem 6== If the degree measures of the angles of a triangle are in the ratio <math>3:3:4</math>, what is the degree measure of the largest angle of the triangle? <math>...")
 
(Solution 4 (Brute Force) NOT RECOMMENDED)
 
(27 intermediate revisions by 14 users not shown)
Line 1: Line 1:
==Problem 6==
+
==Problem==
  
 
If the degree measures of the angles of a triangle are in the ratio <math>3:3:4</math>, what is the degree measure of the largest angle of the triangle?
 
If the degree measures of the angles of a triangle are in the ratio <math>3:3:4</math>, what is the degree measure of the largest angle of the triangle?
Line 5: Line 5:
 
<math>\textbf{(A) }18\qquad\textbf{(B) }36\qquad\textbf{(C) }60\qquad\textbf{(D) }72\qquad\textbf{(E) }90</math>
 
<math>\textbf{(A) }18\qquad\textbf{(B) }36\qquad\textbf{(C) }60\qquad\textbf{(D) }72\qquad\textbf{(E) }90</math>
  
 +
==Solution 1==
  
==Solution==
+
The sum of the ratios is <math>10</math>.  Since the sum of the angles of a triangle is <math>180^{\circ}</math>, the ratio can be scaled up to <math>54:54:72</math> <math>(3\cdot 18:3\cdot 18:4\cdot 18).</math>  The numbers in the ratio <math>54:54:72</math> represent the angles of the triangle.  The question asks for the largest, so the answer is <math>\boxed{\textbf{(D) }72}</math>.
  
The sum of the ratios is <math>10</math>. Since the sum of the angles of a triangle is <math>180^{\circ}</math>, the ratio can be scaled up to <math>54:54:72</math>. The numbers in the ratio <math>54:54:72</math> represent the angles of the triangle.  We want the largest, so the answer is <math>\boxed{\textbf{(D) }72}</math>
+
==Solution 2==
 +
We can denote the angles of the triangle as <math>3x</math>, <math>3x</math>, <math>4x</math>. Due to the sum of the angles in a triangle, <math>3x+3x+4x=180^{\circ}\implies x=18^{\circ}</math>. The greatest angle is <math>4x</math> and after substitution we get <math>\boxed{\textbf{(D) }72}</math>.
 +
 
 +
~MathFun1000
 +
 
 +
==Video Solution (CREATIVE THINKING!!!)==
 +
https://youtu.be/2CmjcUwuYoE
 +
 
 +
~Education, the Study of Everything
 +
 
 +
==Video Solution==
 +
https://youtu.be/rQUwNC0gqdg?t=635
 +
 
 +
https://youtu.be/ykR1ApGP0Qg
 +
 
 +
~savannahsolver
 +
 
 +
==See Also==
 +
{{AMC8 box|year=2017|num-b=5|num-a=7}}
 +
 
 +
{{MAA Notice}}

Latest revision as of 14:27, 26 May 2024

Problem

If the degree measures of the angles of a triangle are in the ratio $3:3:4$, what is the degree measure of the largest angle of the triangle?

$\textbf{(A) }18\qquad\textbf{(B) }36\qquad\textbf{(C) }60\qquad\textbf{(D) }72\qquad\textbf{(E) }90$

Solution 1

The sum of the ratios is $10$. Since the sum of the angles of a triangle is $180^{\circ}$, the ratio can be scaled up to $54:54:72$ $(3\cdot 18:3\cdot 18:4\cdot 18).$ The numbers in the ratio $54:54:72$ represent the angles of the triangle. The question asks for the largest, so the answer is $\boxed{\textbf{(D) }72}$.

Solution 2

We can denote the angles of the triangle as $3x$, $3x$, $4x$. Due to the sum of the angles in a triangle, $3x+3x+4x=180^{\circ}\implies x=18^{\circ}$. The greatest angle is $4x$ and after substitution we get $\boxed{\textbf{(D) }72}$.

~MathFun1000

Video Solution (CREATIVE THINKING!!!)

https://youtu.be/2CmjcUwuYoE

~Education, the Study of Everything

Video Solution

https://youtu.be/rQUwNC0gqdg?t=635

https://youtu.be/ykR1ApGP0Qg

~savannahsolver

See Also

2017 AMC 8 (ProblemsAnswer KeyResources)
Preceded by
Problem 5
Followed by
Problem 7
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
All AJHSME/AMC 8 Problems and Solutions

The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions. AMC logo.png