Homework # 3 - Math 250
The problems on this homework must be done alone. The honor code is in effect.
First name: Last name:
In questions 1, 2, and 3 consider the triangle with vertices A(1,2,3), B(5,5,3), and C(3,4,4).
1. Find cos\(\theta\) where \(\theta\) is the smallest angle in the triangle.
a. -14/15
b. -1/15
c. 0
d. 1/15
e. 14/15
2. Classify this triangle as one of the following.
a. Acute
b. Right
c. Obtuse
3. Find the coordinates of D so that ABCD is a parallogram. Hint: this means that opposite sides must be parallel.
a. (7, 7, 4)
b. (3, 3, 2)
c. (-1, 1, 4)
d. (0, 0 ,0)
e. (7, 8, 3)
4. For how many different values of t would the vectors 〈t, t, -1〉,〈t, 1, 6〉 be orthogonal?
a. None
b. One
c. Two
d. Three
e. Infinitely many
5. Find the area of parallelogram ABCD.
a. 9√3/2
b. 6√3
c. 15√3/2
d. 9√3
e. 21√3/2
6. Find the area of triangle ABC.