- Grade: Geometry
- Chapter: Law of Sines, Law of Cosines and Triangle Area
- Common Core: G-SRT.D.9, G-SRT.D.10, G-SRT.D.11
- Time: 45 minutes
- Total: 20 points (Question 1: 2 pts; Question 2: 2 pts; Question 3: 2 pts; Question 4: 2 pts; Question 5: 2 pts; Question 6: 2 pts; Question 7: 3 pts; Question 8: 3 pts; Question 9: 2 pts)
Question 1: Area of a triangle (2 points)
Find the area to the nearest tenth of a square foot.
Question 2: Law of Sines, find a side (2 points)
Find side \(b\) to the nearest tenth.
Question 3: Law of Sines, find angles (2 points)
In triangle ABC, \(a=22\), \(b=16\) and \(A=75^{\circ}\). Find \(m\angle B\) and \(m\angle C\) to the nearest tenth of a degree. (1 point each)
Question 4: Law of Cosines, find a side (2 points)
Find \(c\) to the nearest tenth.
Question 5: Largest angle of a triangle (2 points)
A triangle has sides 9, 12 and 17. Find the measure of its largest angle to the nearest tenth of a degree.
Question 6: Choosing a law (2 points)
Name the law you would use first in each case and explain your choice.
- A surveyor knows two sides of a triangle and the angle between them and needs the third side. (1 point)
- A surveyor knows two angles of a triangle and the side opposite one of them and needs another side. (1 point)
Question 7: Proof of the area formula (3 points)
In acute triangle ABC, \(a=BC\) and \(b=AC\). Complete the proof that \(\text{Area}=\frac{1}{2}ab\sin C\) by writing the reasons (a) through (e).
| Step | Statements | Reasons |
|---|---|---|
| 1 | Draw altitude \(\overline{AD}\) to \(\overline{BC}\) with \(AD=h\) | (a) |
| 2 | \(\text{Area}=\frac{1}{2}ah\) | (b) |
| 3 | \(\sin C=\frac{h}{b}\) | (c) |
| 4 | \(h=b\sin C\) | (d) |
| 5 | \(\text{Area}=\frac{1}{2}ab\sin C\) | (e) |
Question 8: Two ships (3 points)
Ship 1 sails 28 mi and ship 2 sails 40 mi. How far apart are the ships? Round to the nearest tenth of a mile.
Question 9: Area of a lot (2 points)
A triangular lot has sides of 85 ft and 110 ft that meet at a \(52^{\circ}\) angle. Find its area to the nearest square foot.
See every chapter on the Geometry math page.



