Points to Remember

Points to Remember

·           Two triangles are similar

(i) if their corresponding angles are equal

(ii) their corresponding sides are in the same ratio or prvoportional.

·           Any congruent triangles are similar but the converse is not true

·           AA similarity criterion is same as the AAA similarity criterion.

·           If one angle of a triangle is equal to one angle of another triangle and the sides If one angle of a triangle is equal to one angle of another triangle and the sides

·           If three sides of a triangle are proportional to the corresponding sides of another triangle, then the two triangles are similar (SSS)

·           If two triangles are similar then the ratio of the corresponding sides is equal to the ratio of the corresponding perimeters.

·           The ratio of the area of two similar triangles are equal to the ratio of the squares of their corresponding sides.

·           A tangent to a circle will be perpendicular to the radius at the point of contact.

·           Two tangents can be drawn from any exterior point of a circle.

·           The lengths of the two tangents drawn from an exterior point to a circle are equal.

·           Two direct common tangents drawn to two circles are equal in length.