in Fig. 2.20 DE 10Q and DF OR Show that
F
0
R
in 221. A Band Care points on Op. OQ and
OR respectively such that ABPQ and ACU PR.
Show that BC OR
7. Using Theorem 2.1. prove that a line drawn through
the mid-point of one side of a triangle parallel to
another side bisects the third side (Recall that you
have proved it in Class IX)
& Using Theorem 2.2. prove that the line joining the
mid points of any two sides ora triangle is parallel
to the third side. (Recall that you have done it in
Fig. 2.20
B
9. ABCD is a traperium in which AB | DC and its
0
diagonals intersect each other at the point O. Show
АО
R
that
Fig. 2.21
10. The diagonals of a quadrilateral ABCD intersect each other at the point o such that
CO
Show that ABCD is a trapezium
BO DO
4 Criteria for Similarity of Triangles
n the previous section, we stated that two triangles are similar, if(i) their corresponding
ngles are equal and (ii) their corresponding sides are in the same ratio (or proportion)
That is, in A ABC and A DEF. if
(1) ZA= 2D, B= 2E, C= F and
AB
DE
BC CA
EF FD
then the two triangles are similar (see Fig.2.22).
BA
AC
Fio 2.22
Answers
Answer:
I didn't understand this question so I can't answer this question
triangle has three sides and three angles
right arrow
The three angles always add to 180°
Equilateral, Isosceles and Scalene
There are three special names given to triangles that tell how many sides (or angles) are equal.
There can be 3, 2 or no equal sides/angles:
Equilateral Triangle
Equilateral Triangle
Three equal sides
Three equal angles, always 60°
Isosceles Triangle
Isosceles Triangle
Two equal sides
Two equal angles
Scalene Triangle
Scalene Triangle
No equal sides
No equal angles
How to remember? Alphabetically they go 3, 2, none:
Equilateral: "equal"-lateral (lateral means side) so they have all equal sides
Isosceles: means "equal legs", and we have two legs, right? Also iSOSceles has two equal "Sides" joined by an "Odd" side.
Scalene: means "uneven" or "odd", so no equal sides.
What Type of Angle?
Triangles can also have names that tell you what type of angle is inside:
Acute Triangle
Acute Triangle
All angles are less than 90°
Right Triangle
Right Triangle
Has a right angle (90°)
Obtuse Triangle
Obtuse Triangle
Has an angle more than 90°