Friday, February 20, 2026

Geometry Problems of the Day (Geometry Regents, August 2025 Part I)



This exam was adminstered in August 2025.

More Regents problems.

August 2025 Geometry Regents

Part I

Each correct answer will receive 2 credits. No partial credit.


1. An equilateral triangle is continuously rotated around one of its altitudes. The three-dimensional object formed is a

(1) cone
(2) sphere
(3) cylinder
(4) pyramid

Answer: (1) cone


Imagine an equilateral triangle taped to a lollipop stick that running from one corner and through the midpoint of the opposite side. If you were to spin the stick, the stuff that the triangle will pass through will form a cone. That is Choice (1).

It is impossible to get any of the others from a triangle.




2. On the set of axes below, quadrilateral BDGF is rotated 90 degrees clockwise about the origin and then reflected over the y-axis. The image of quadrilateral BDGF is quadrilateral MQSP.

Side BD will always map onto

(1) MP
(2) PS
(3) MQ
(4) SQ

Answer: (3) MQ


Follow the movement. When BDGF is rotated 90 degree clockwise, the image appears in Quadrant IV with BD on top, closest to the x-axis. When this image is reflected across the y-axix, B'D' maps onto MQ, which is Choice (3).




3. In right triangle JOE, hypotenuse JO = 31.8 and m∠J = 38°. To the nearest tenth, the length of EJ is

(1) 19.6
(2) 25.1
(3) 40.4
(4) 51.7

Answer: (2) 25.1


Angle E is the right angle. EJ is adjacent to angle J, and you're given the hypotenuse. That means that you need to use cosine.

cos 38 = x / 31.8
x = 31.8 cos 38 = 25.0587... = 25.1

Choice (2) is the correct answer.




4. The hemisphere below has a radius of 8 cm.


To the nearest cubic centimeter, the volume of the hemisphere is

(1) 201
(2) 268
(3) 1072
(4) 2145

Answer: (3) 1072


Use the formula for the Volume of a Sphere and then take half of it. The formula is V = (4/3) π r3.

So V = (1/2) (4/3) π (8)3 = 1072.33...

Choice (3) is the correct choice.

If you'd forgotten the 1/2, you would've gotten choice (4).

If you'd forgotten the 1/2 AND halved the radius to 4, you would've gotten Choice (2).

If you used π r2, you would've gotten Choice (1).
Yes, I needed to figure that one out. I wanted to know!




5. In parallelogram ABCD, diagonals AC and BD intersect at E. Which information is sufficient to prove ABCD is a rhombus?

(1) AE ≅ EC
(2) AC ≅ BD
(3) AB ⊥ BC
(4) AC ⊥ BD

Answer: (4) AC ⊥ BD


In a parallelogram, if the two diagonals are perpendicular, then the parallelogram is a rhombus.




6. Trapezoid JOSH, shown below, has non-parallel sides JH and OS, m∠J = 65°, m∠O = 30°, m∠OSA = 80°, and m∠SHU = 60°.



(1) 55°
(2) 60°
(3) 65°
(4) 70°

Answer: (4) 70°


SAO is a triangle, and the sum of its angles is 180 degrees. Because m∠O = 30° and m∠OSA = 80°, then m∠OAS = 70°. Angle OAS and angle HSA are alternate interior angles. Since JO || SH, then ∠OAS ≅ ∠OSA.

Therefore, m∠OSA = 70°, which is Choice (4).




7. In △ABC below, points D and E are on such that AC. DE || AC.

If AD = 8, DB = 4, and DE = 6, what is the length of AC



(1) 24
(2) 18
(3) 12
(4) 10

Answer: (2) 18


The two triangles are have sides that are proportional because they are similar triangles. If AD = 8 and DB = 4, then AB = 12, and the scale factor is 3.

Therefore, if DE = 6 then AC = 6 * 3 = 18.

Choice (2) is the correct answer.




8. On the set of axes below, circle C has a center with coordinates (2,–1).

Which equation represents circle C?



(1) (x - 2)2 + (y + 1)2 = 25
(2) (x - 2)2 + (y + 1)2 = 16
(3) (x + 2)2 + (y - 1)2 = 25
(4) (x + 2)2 + (y - 1)2 = 16

Answer: (1) (x - 2)2 + (y + 1)2 = 25


The formula for the equation of a circle is (x - h)2 + (y - k)2 = r2, where (h,k) is the coordinates of the center and r is the length of the radius.

The center point C is at (1,-2), so eliminate Choices (3) and (4).

If you count across from C, you'll see that the radius is 5. (5)2 = 25, so the correct answer is Choice (1).


More to come. Comments and questions welcome.


MY NEWEST BOOK IS OUT


Burke's Lore Briefs: Yesterday's Villains, the following to Tomorrow's Heroes is now available on Amazon and Kindle Unlimited.

If Heroes who don't die live long enough to become the villain, what happens to Villains who live long enough? When do schemes of global conquest become dreams of a quiet place away from all those annoying people you once wanted to subjugate? And does anyone really want to rule over the world's ashes if it means we can't have nice things?


My older books include three more books in my Burke's Lore Briefs series, and the anthologies A Bucket Full of Moonlight and In A Flash 2020.

Vampires, werewolves, angels, demons, used-car salesmen, fairies, superheroes, space and time travel, and little gray aliens talking to rock creatures and living plants.

Plus pirates, spies, horror, and kindergarten noir!

If you enjoy my books, please consider leaving a rating or review on Amazon or on Good Reads. Thank you!


No comments: