All PSAT Math Resources
Example Question #172 : Triangles
Three points in the xy-coordinate system form a triangle.
The points are .
What is the perimeter of the triangle?
Drawing points gives sides of a right triangle of 4, 5, and an unknown hypotenuse.
Using the pythagorean theorem we find that the hypotenuse is .
Example Question #1 : How To Find The Perimeter Of A Right Triangle
Based on the information given above, what is the perimeter of triangle ABC?
Consult the diagram above while reading the solution. Because of what we know about supplementary angles, we can fill in the inner values of the triangle. Angles A and B can be found by the following reductions:
A + 120 = 180; A = 60
B + 150 = 180; B = 30
Since we know A + B + C = 180 and have the values of A and B, we know:
60 + 30 + C = 180; C = 90
This gives us a 30:60:90 triangle. Now, since 17.5 is across from the 30° angle, we know that the other two sides will have to be √3 and 2 times 17.5; therefore, our perimeter will be as follows: