<p>With less than a week to go, why not make a geometry thread with little pointers to remember. I myself have little problem with algebra but constantly get geometry questions wrong. I’ll start by listing some formulas and some of the problems that i have. ( This is plane, solid, and coordinate)</p>
<p>Circles:
A= PiR^
C= 2PiR=DPi
Semi Circle: Divide Area and Circumfrence by 2
Arc= Circumfrence, Sector= Area, angle/360 = percentage of area or circumfrence
Shaded Area- Total- unshaded
Tangent= 90 degrees
Radii are always equal</p>
<p>Angles:
angles around intersection of two lines= 360
A line forms a 180 degree angle so two angles by a line will be supplementary
Triangle has 180, Circle and Quad’s have 360 “N” gon has 180 X (N-2)</p>
<p>And so on…
My problems are “reflection” problems around the x and y axis, solid geometry tips, and parallel lines. Any tips on how to solve these?</p>
<p>You should give an example.</p>
<p>For reflection problems, imagine placing a mirror on the axis of reflection. For example, if a figure is reflected over the x-axis, place a mirror on the x-axis facing the figure. Then look in the mirror. What does the figure in the mirror look like? This is the reflection.</p>
<p>Remember that Root 2 or Root 3 in the answer choice signals a 45:45:90 triangle or a 30:60:90 triangle. And pi in the answer choices signals the need for the formula for the area of a circle OR the circumference of a circle.</p>
<p>The sum of the lengths of any two sides of a triangle is always greater than the length of the remaining side.</p>
<p>Similar triangles are often disguised.</p>
<p>Area of an equilateral triangle = (s^2/4)root 3</p>
<p>Every equilateral triangle has two 30:60:90 triangles.</p>
<p>Every square has two 45:45:90 triangles.</p>
<p>Area of a parallelogram = length times height.</p>
<p>To find the sum of the interior angles of a regular polygon, divide the polygon into triangles. Multiply the number of triangles by 180. </p>
<p>If you are given a right circular cylinder, you will either be asked about the volume, or a right triangle created from the center of the bases and a line on the edge of a base.</p>
<p>For geometric perception questions, use objects in the room to visualize the figures.</p>