Proportions review

What is a ratio?


A ratio is teh comparison of the quantity of two properties or items




What is a proportion?


Proportion is an equation that states that two ratios are equal for instance a/b = c/d




How do I convert from one unit to another using proportions?


Make a proportion quation using The conversion ratio and The a conversion statement for the unknown For example To convert 2 feet into inches make two statements 1 foot =12 inches 2 feet = x write them as ratios 1 foot/12 inches = 2 feets/x cross multiply x = 24 feet




How to find arc length, curcumference or angle using proportion


x degrees/360 degrees = arc length /circumference For example: If the circumference of a circle is 24cm, what is the central angle that subtends an arc AB whose length is 4cm? x degrees/360 = 4cm/24cm cross multiply 24 x = 1440 divide both sides by 24 x = 60 degrees




How to find side length of similar triangles


The scale factor above is n This means that each side on the smaller triangle is multiplied by n to get the corresponding side length of the larger triangle. If the side lenght of the base of the small traingle is 4cm, and n is 2. then x/2x = 4/a cross multiply ax = 8x a = 8cm




How to solve problems where two variables x and y are directly proportional





How to solve problems where the two variable x and y are inversely proportional






About us | Contact us| Privacy policy | Terms of use

 

© 2019 by Free SAT® Practice. All rights reserved  

 

SAT® is a trademark registered by the College Board, which was not involved with the creation of, is not affiliated with, and does not endorse services provided by freesatpractice.org.