12 multiple-choice questions, progressively harder.
A convex trapezoid has perpendicular height 666 cm and area 114114114 square cm. Its longer parallel base exceeds its shorter base by 101010 cm. Find the shorter base.
Solution
Correct answer: D
Let the shorter base be bbb cm, so the longer is b+10b+10b+10 cm.
In a rhombus each side is 101010 cm and one full diagonal is 121212 cm. Find the area.
Correct answer: B
Each half of the known diagonal is 666 cm. A right triangle with hypotenuse 101010 cm has other leg 888 cm, so the second full diagonal is 161616 cm.
In convex kite ABCDABCDABCD, the equal-side pairs meet at AAA and CCC. Diagonals meet at OOO. Given BOBOBO is 555 cm, AOAOAO is 444 cm, and area 757575 square cm, find OCOCOC.
Correct answer: C
AC bisects BD, so BD=10BD=10BD=10 cm. First find the full diagonal AC.
In a convex quadrilateral, diagonal ACACAC is 121212 cm and area 102102102 square cm. The perpendicular distance from BBB to ACACAC is 555 cm. Find the perpendicular distance from DDD to ACACAC.
Correct answer: A
The two triangle heights add in the area computation.
A convex trapezoid has one leg perpendicular to the bases. Its bases are 999 cm and 171717 cm and its other leg is 101010 cm. Find its area.
The horizontal difference of the bases is 888 cm. The right triangle at the slanted leg gives height 666 cm.
A rhombus has area 120120120 square cm and side length 131313 cm. One diagonal is 101010 cm. What are the other diagonal and the height to a side?
121212 cm;
Height 12013\tfrac{120}{13}13120 cm
242424 cm;
Height 131313 cm
Height 6013\tfrac{60}{13}1360 cm
Use the diagonal formula for the other diagonal, then the parallelogram formula for the side height.
A convex trapezoid has area 999999 square cm. Its bases measure (x+2)(x+2)(x+2) cm and (2x+1)(2x+1)(2x+1) cm and its height is 666 cm. Find both base lengths.
The base sum is 333333 cm.
Substitution gives bases 121212 cm and 212121 cm.
A convex kite has area 126126126 square cm. Its full diagonal ACACAC is 212121 cm, and AC bisects BD at O. The point O divides AC into parts 666 cm and 151515 cm. Find BO.
The area determines the full diagonal BD; then use its bisection.
Which change to the givens guarantees that diagonal lengths ppp and qqq determine area 12pq\tfrac12pq21pq for a convex quadrilateral?
A right-angle intersection makes the diagonal parts perpendicular heights. Neither bisection alone nor a parallel-side condition supplies that angle.
A convex quadrilateral has perpendicular diagonals. Their lengths are (x+1)(x+1)(x+1) cm and 121212 cm. Its area is 545454 square cm. What is the diagonal length expressed by x+1x+1x+1?
The question asks for the full diagonal, not for xxx.
A convex trapezoid has midsegment 141414 cm and area 112112112 square cm. Its longer base is 181818 cm. Find its height and shorter base.
Height 444 cm;
Shorter base 101010 cm
Height 888 cm;
Shorter base 444 cm
The midsegment is the average of the bases, so area equals midsegment times height.
In a convex quadrilateral, diagonal ACACAC is 202020 cm. The perpendicular distances of BBB and DDD to AC are xxx cm and (x+3)(x+3)(x+3) cm. Its area is 130130130 square cm. Find the two distances.
Add the two triangle areas and solve.
The other distance is 888 cm.
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