# geometry

posted by .

The triangle DEF has vertices D(-1,3)
E(7,1) and F(4,6). Classify the triangle as:
a) isosceles or scalene
b) right angled or not

• geometry -

An isosceles triangle has at least two equal sides.
To check this, we find the difference between the end-points of each of the sides, and from that, we calculate the length using Pythagoras Theorem.
D-E (-1,3)-(7,1)=(-1-7,3-1)=(-8,2)
L=√(8²+2*sup2;)=√68
E-F (7,1)-(4,6)=(7-4,1-6)=(3,-5)
L=√(3²+(-5)²)=√34
F-D (4,6)-(-1,3)=(4-(-1),6-3)=(5,3)
L=√(5²+3²)=√34

Since mEF=mFD, we conclude that the triangle DEF is isosceles.

Since mEF²+mFD²=mDE², we conclude that ∠EFD is a right angle, thus the triangle is a right-triangle.

• geometry-corr -

L=√(8²+2²)=√68

## Similar Questions

1. ### Math

A triangle has 2 angles that measure 60 each. Which of the following best describes thiz triangle. A. Right isoseles triangle B. Equilateral triangle C. Obtuse isosceles triangle D. Acute scalene triangle
2. ### Math-CHECK PLEASE

Which of the statements is ALWAYS TRUE? A-A right triangle is a scalene triangle. B-An equilateral triangle is an isosceles triangle. C-An isosceles triangle is an obtuse triangle. D-A right triangle is an acute triangle. I got either
3. ### math

The vertices of a triangle are listed below. H(-2,4), I(22,4), J(10,-1) Which of the following correctly classifies the triangle?
4. ### Math (Geometry)

The perimeter of right triangle ABC is equal to the perimeter of isosceles triangle DEF. The lengths of the legs of the right triangle are 6 and 8. If the length of each side of the isosceles triangle is an integer, what is the greatest …
5. ### Math

Again i wrote the question wrong. 4. Classify the triangle with angles measuring 69º, 42º, and 69º. A. right B. equilateral C. isosceles acute D. isosceles obtuse You said isosceles but i didn't know whether it was C or D. Here's …
6. ### Help me

11. Name the triangles that are classified by angles. right, scalene, isosceles scalene, isosceles, equilateral acute, right, obtuse obtuse, isosceles, acute 12. Classify the triangle by side length and angle measurement. scalene, …
7. ### Math

Can someone please check to see if I answered these true and false statements correctly?
8. ### Math

Which triangle is NOT possible to construct?
9. ### math

This question is suppose to be simple but i keep getting it wrong Triangle LMN has vertices L(1, 6), M(6, 3) and N(5, 7). What type of triangle is Triangle LMN?
10. ### Math 8th

How could I solve this? Multiple Choice Classify the triangle according to side length and angle measurement. A right triangle A. isosceles; right B. equilateral; obtuse C. scalene; acute D. scalene; right

More Similar Questions