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Texas STAAR Geometry Formula Sheet

Curated study set

Worth knowing before you print anything: Texas does not have a STAAR Geometry exam. The STAAR end-of-course assessments are Algebra I, Biology, English I, English II, and U.S. History, and the Texas Education Agency publishes mathematics reference materials for grades 3–8 and Algebra I only — there is no official STAAR Geometry reference chart to mirror. This preset exists because thousands of Texas students and teachers search for one anyway, and it gives them something accurate instead: a curated high-school geometry set aligned to the Texas Geometry TEKS (§111.41).

On the geometry side you get area for rectangles, triangles, trapezoids, rhombuses, and circles; surface area and volume for prisms, pyramids, cylinders, cones, and spheres. On the coordinate side you get the distance formula, the midpoint formula, and slope. For right triangles you get the Pythagorean theorem, the 45-45-90 and 30-60-90 side ratios, and SOH-CAH-TOA for sine, cosine, and tangent. Together these cover the formula-driven work of a full Texas Geometry course.

Because no chart is handed to you in a Texas geometry class the way one is on an exam, the smart strategy is fluency rather than lookup: knowing which formula applies and how to substitute quickly. Every formula on this sheet links to an interactive explorer where you can drag a shape, watch the value update, and read the full step-by-step substitution. The bonus section adds equations of a line and the laws of sines and cosines for students pushing further.

If you are preparing for an actual STAAR administration, the one you want is Algebra I, and TEA does publish an official Algebra I reference chart — the coordinate-geometry and right-triangle sections of this preset are the parts that carry over. If instead you are revising for a district geometry final, a course exam, or the geometry strand of the SAT or ACT, the full set here is a complete year-in-review. Either way, confirm with your teacher which formulas your specific assessment provides.

Because Texas courses are built on the Texas Essential Knowledge and Skills (TEKS), pair each formula here with the process standards it supports — applying mathematics to real-world problems and communicating a clear solution — so a printed sheet becomes a map of the reasoning your class actually rewards, not just a list of symbols. Choose A4 or US Letter, trim the list to the unit you are reviewing, and print a clean two-column reference.

Official source: https://tea.texas.gov/data-reports/staar/staar-mathematics-resources

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Texas STAAR Geometry — Formula Sheet

Verified formulas · GeometryFormula.com

Rectangle
AreaA=l⋅wA = l \cdot w
PerimeterP=2(l+w)P = 2(l + w)
Diagonald=l2+w2d = \sqrt{l^2 + w^2}
Triangle
Area (base & height)A=12bhA = \tfrac{1}{2} b h
Area (Heron’s)A=s(s−a)(s−b)(s−c)A = \sqrt{s(s-a)(s-b)(s-c)}
Semiperimeters=a+b+c2s = \dfrac{a+b+c}{2}
PerimeterP=a+b+cP = a + b + c
Trapezoid
AreaA=12(a+b)hA = \tfrac{1}{2}(a + b)h
Medianm=a+b2m = \dfrac{a + b}{2}
Rhombus
AreaA=12d1d2A = \tfrac{1}{2} d_1 d_2
Sides=(d1/2)2+(d2/2)2s = \sqrt{(d_1/2)^2 + (d_2/2)^2}
PerimeterP=4sP = 4s
Circle
AreaA=πr2A = \pi r^2
CircumferenceC=2πrC = 2\pi r
Diameterd=2rd = 2r
General prism
VolumeV=BhV = B h
Surface areaSA=2B+PhSA = 2B + Ph
Cylinder
VolumeV=πr2hV = \pi r^2 h
Lateral surfaceLSA=2πrhLSA = 2\pi r h
Surface areaSA=2πr(r+h)SA = 2\pi r(r + h)
Cone
Slant heightℓ=r2+h2\ell = \sqrt{r^2 + h^2}
VolumeV=13πr2hV = \tfrac{1}{3}\pi r^2 h
Lateral surfaceLSA=πrℓLSA = \pi r \ell
Surface areaSA=πr(r+ℓ)SA = \pi r(r + \ell)
Sphere
VolumeV=43πr3V = \tfrac{4}{3}\pi r^3
Surface areaSA=4πr2SA = 4\pi r^2
Pyramid
Slant heightℓ=(b/2)2+h2\ell = \sqrt{(b/2)^2 + h^2}
VolumeV=13b2hV = \tfrac{1}{3} b^2 h
Lateral surfaceLSA=2bℓLSA = 2 b \ell
Surface areaSA=b2+2bℓSA = b^2 + 2 b \ell
Distance formula
Distanced=(x2−x1)2+(y2−y1)2d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}
Midpoint formula
MidpointM=(x1+x22,y1+y22)M = \left(\dfrac{x_1 + x_2}{2}, \dfrac{y_1 + y_2}{2}\right)
Slope
Slopem=y2−y1x2−x1m = \dfrac{y_2 - y_1}{x_2 - x_1}
Equations of a line
Slope-intercepty=mx+by = mx + b
Point-slopey−y1=m(x−x1)y - y_1 = m(x - x_1)
StandardAx+By=CAx + By = C
Pythagorean theorem
Right trianglea2+b2=c2a^2 + b^2 = c^2
Special right triangles
45–45–90x:x:x2x : x : x\sqrt{2}
30–60–90x:x3:2xx : x\sqrt{3} : 2x
Trig ratios (SOH-CAH-TOA)
Sinesin⁡θ=opphyp\sin\theta = \dfrac{\text{opp}}{\text{hyp}}
Cosinecos⁡θ=adjhyp\cos\theta = \dfrac{\text{adj}}{\text{hyp}}
Tangenttan⁡θ=oppadj\tan\theta = \dfrac{\text{opp}}{\text{adj}}
Law of sines
Law of sinesasin⁡A=bsin⁡B=csin⁡C\dfrac{a}{\sin A} = \dfrac{b}{\sin B} = \dfrac{c}{\sin C}
Law of cosines
Law of cosinesc2=a2+b2−2abcos⁡Cc^2 = a^2 + b^2 - 2ab\cos C
Free printable geometry formulas · GeometryFormula.com · CC BY-SA 4.0

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Frequently asked questions

What formulas are on the Texas STAAR sheet?

Texas STAAR has no Geometry end-of-course exam — TEA publishes reference materials for grades 3–8 and Algebra I only. This is a curated high-school geometry set aligned to the Texas Geometry TEKS. Use the builder to see every formula, add bonus formulas, and print a clean A4 or US Letter copy.

Is this Texas STAAR formula sheet free to print?

Yes — no sign-up, no watermark, no cost. Print it or save it as a PDF from your browser as often as you like.

Can I customize the sheet?

Yes. The preset pre-checks the aligned formulas; you can add or remove any formula, switch paper size, and copy a shareable link to your exact sheet.