Solve the following proportions

a = 9 b = 7 c = 6 d = ±6

Using Proportions to Solve Geometry Problems Sections

Ratios & Proportions A ratio is a comparison of two values, usually showed as a fraction. A proportion is an equation in which two ratios are set equal to each other.

Properties of Proportions The proportion is still equal if: 1.You take the reciprocal of both sides. 2.You switch the numbers along one or both diagonals. 3.You add the value in the denominator to the numerator on both sides.

Scale Factor Two polygons are similar polygons if corresponding angles are congruent and corresponding side lengths are proportional. The scale or scale factor is the ratio that describes how the dimensions of the two figures are related.

List all pairs of congruent angles. Check that the ratios of corresponding side lengths are equal. What is the scale factor?

Perimeters of Similar Polygons If two polygons are similar, then the ratio of their perimeters is equal to the ratio of their corresponding side lengths.

Perimeters of Similar Figures

Angle-Angle Similarity Postulate (AA) If two angles of one triangle are congruent to two angles of another triangle, then the two triangles are similar.

Side-Side-Side Similarity Theorem If the corresponding side lengths of two triangles are proportional, then the triangles are similar.

Side-Angle-Side Similarity Theorem If an angle of one triangle is congruent to an angle of a second triangle and the lengths of the sides including these angles are proportional, then the triangles are similar.

Show that each set of triangles is similar

Show that the two triangles are similar.