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Law of Sines, Law of Cosines and Triangle Area: Geometry Math Test – PDF Download

    Law of Sines, Law of Cosines and Triangle Area – Geometry math test
    This test covers the area formula, the Law of Sines, the Law of Cosines and applications under Common Core standards G-SRT.D.9, G-SRT.D.10 and G-SRT.D.11. It has 9 questions worth 20 points and takes about 45 minutes with a scientific calculator in degree mode.
    Test information
    • 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)

    ABC14 ft20 ft38°
    Sides 14 ft and 20 ft with a 38 degree included angle.

    Find the area to the nearest tenth of a square foot.

    Question 2: Law of Sines, find a side (2 points)

    ABC18b42°67°
    Triangle with two angles and a side.

    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)

    ABC1317c105°
    Two sides 13 and 17 with included angle 105 degrees.

    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.

    1. A surveyor knows two sides of a triangle and the angle between them and needs the third side. (1 point)
    2. 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 2Ship 1Harbor28 mi40 mid64°
    Two ships leave a harbor on courses 64 degrees apart.

    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.

    Law of Sines, Law of Cosines and Triangle Area: Geometry test answer key

    See every chapter on the Geometry math page.

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