+0  
 
0
117
3
avatar

Find the area of triangle PQR if PQ = QR = 12 and angle PQR = 120.

 Mar 29, 2020
 #1
avatar+626 
+1

Draw:

- An isosceles triangle that has a vertex angle of 120.

- If you draw from Q to the midpoint of PR, you can create two 30-60-90 triangles.

 

Solve:

Knowing that the triangles are 30-60-90 with the hypotenuse given, can you find the height and base of the triangle and solve?

 Mar 29, 2020
 #2
avatar+1948 
+1

AnExtremelyLongName:

 

This is an isosceles triangle, with angles 120, 30, and 30. It says in the question that angle PQR is 120 degrees, which makes the other 30 degrees.

 Mar 29, 2020
 #3
avatar+626 
0

Yes I know. What are you implying? There are multiple ways to solve this.

 

 - The easiest (in my opinion) is my first post.

 

 - Another method is to apply the law of cosines to solve for the last missing side, then use Heron's Formula to calculate the area

 

There may be more!

AnExtremelyLongName  Mar 30, 2020

14 Online Users

avatar
avatar