12 multiple-choice questions, progressively harder.
The angles AAA and BBB have different sines. What expression equals the common side-over-sine ratio in triangle ABCABCABC?
Solution
Correct answer: D
Call the common ratio kkk. Then each length is kkk times the sine of its opposite angle.
The sine difference is nonzero, so divide by it.
In an acute SSA construction, the perpendicular foot HHH is 15 units ahead of AAA. Its distance to the circle center CCC is 8 units. The circle radius is 10 units. What lengths can ABABAB have?
Correct answer: B
Any crossing BBB is 10 units from CCC, so the right triangle with legs CHCHCH and HBHBHB fixes the distance from HHH to a crossing.
Both positions are ahead of AAA, at distances 15 minus 6 and 15 plus 6.
Two triangles share the same acute SSA data and the same segment ACACAC. One uses the circle crossing nearer to AAA on ray ABABAB. Which triangle has greater area?
Correct answer: C
The two triangles use the same perpendicular height hhh from CCC to the ray line. For either choice of BBB, the area is
The farther crossing gives a longer base and therefore greater area.
On one shore, stations AAA and BBB are 135 m apart. The interior angles at AAA and BBB toward marker CCC are 27∘27^\circ27∘ and 83∘83^\circ83∘. All three points lie in one horizontal plane. How far is CCC from AAA to the nearest tenth of a meter?
Correct answer: A
First find the angle opposite the known baseline.
The distance ACACAC is opposite BBB.
The known angle is 105∘105^\circ105∘ and bbb is 12 units. Which condition on the radius aaa is necessary and sufficient for a valid triangle?
The perpendicular foot HHH is behind AAA. For any point BBB ahead of AAA, the Pythagorean theorem gives
As BBB advances, only HBHBHB changes, so the distance from CCC grows strictly from 12. A radius above 12 reaches the ray once. At 12 the intersection is the excluded start.
For a triangle with a fixed known pair A,aA,aA,a, which expression gives its perimeter once BBB and CCC are known?
Every side equals the sine of its opposite angle times the common multiplier a/sinAa/\sin Aa/sinA. Add the three sides using that multiplier.
In an SSA problem, an inverse sine calculation gives an acute candidate B1B_1B1. Under exactly which condition does its supplement give a valid triangle?
Substitute the supplement into the angle sum.
That candidate is valid precisely when CCC is positive.
When angle AAA measures 45∘45^\circ45∘ and side bbb is 26 units long, there is one SSA triangle and it has a right angle at BBB. What must aaa be?
The circle reaches the perpendicular foot and is tangent to the ray. Its radius equals the height.
Angle AAA of triangle ABCABCABC measures 25∘25^\circ25∘. The lengths of aaa and bbb are 14 cm and 24 cm, respectively. What are all the possible lengths of ABABAB, to the nearest tenth of a centimeter?
Start with the sine equation.
The acute candidate is about 46.4∘46.4^\circ46.4∘ and leaves CCC about 108.6∘108.6^\circ108.6∘.
Its supplement is about 133.6∘133.6^\circ133.6∘ and leaves CCC about 21.4∘21.4^\circ21.4∘.
In each case use 14sinC/sin25∘14\sin C/\sin25^\circ14sinC/sin25∘ with the unrounded angle.
A crew measures angle AAA as 29∘29^\circ29∘. The lengths of aaa and bbb are 18 m and 24 m, respectively. Two positions on ray ABABAB satisfy these readings. A field note says the angle at BBB is acute. Which position matches?
The two sine candidates are about 40.3∘40.3^\circ40.3∘ and 139.7∘139.7^\circ139.7∘. The field note selects the smaller.
Angle AAA measures 150∘150^\circ150∘. The lengths of bbb and aaa are 20 and 12, respectively. The perpendicular distance from CCC to the full ray line is 10. Where are the two circle intersections with that full line?
The circle reaches the line because its radius exceeds the height.
On the forward ray, distance from CCC starts at 20 and increases. Since the radius is below 20, neither crossing lies at or ahead of AAA.
In triangle ABCABCABC, angles AAA and BBB measure 39∘39^\circ39∘ and 84∘84^\circ84∘, respectively. Side ccc is 22 cm long. Which report of aaa and bbb, respectively, matches the givens to the nearest tenth of a centimeter?
Angle CCC measures 57∘57^\circ57∘. Multiply the common ratio by each requested sine.
The side order matches the angle order, and 26.1 cm is less than the sum of 16.5 cm and 22 cm.
Reset this practice set?
This clears every answer you have given and starts the set again from question 1.