Skip to main content

class ix ncert maths..lesson 9 ..ex.9.3 q 3


AD is the median of ΔABC. Therefore, it will divide ΔABC into two triangles of equal areas.
∴ Area (ΔABD) = Area (ΔACD)
⇒  ... (1)
In ΔABD, E is the mid-point of AD. Therefore, BE is the median.
∴ Area (ΔBED) = Area (ΔABE)
⇒ Area (ΔBED) = Area (ΔABD)
⇒ Area (ΔBED) = Area (ΔABC) [From equation (1)]
⇒ Area (ΔBED) = Area (ΔABC)

Popular posts from this blog

Acids, Bases and salts extra qus

1.    What is an acid? Solution: An acid is a hydrogen-containing chemical compound which, when dissolved in water, gives hydrogen ion (H + ) or hydrated hydrogen ion (H 2 O. H + ) or hydronium ion (H 3 O + ).   2.    What are bases and alkalies? Solution: Oxides and hydroxides of metals and metal like radicals (e.g., NH4 +  ions) are called bases. Bases ionise to give OH -  ions in aqueous solution. Bases may be soluble or insoluble in water. The soluble bases are called alkalies. Thus all alkalies are bases but all bases are not alkalies. Examples NaOH and Cu (OH) 2  both are bases, but, since NaOH is soluble in water, it is an alkali. On the other hand, since Cu (OH) 2  is insoluble in water, it is not an alkali. Other examples of alkalies are KOH, Ca (OH) 2  and NH 4 OH.   3.    Define pH. Solution: pH of a given solution is the negative logarithm to the base 10 of the hydrogen ion concentration, [H +...
Read more

Project Tiger

Project Tiger  is a wildlife conservation movement initiated in  India  in 1973 to protect  tigers . The project aims at tiger conservation in specially constituted  tiger reserves  representative of various regions throughout India and strives to maintain viable populations of Bengal tigers in their natural environment. In 2008 there were more than 40 Project Tiger reserves covering an area over 37,761 km 2  (14,580 sq mi). Project Tiger helped to increase the population of these tigers from 1,200 in the 1970s to 3,500 in 1990s. However, a 2008 census held by the Government of India revealed that the tiger population had dropped to 1,411. Since then the government has pledged US$153 million to further fund the project, set-up a Tiger Protection Force to combat  poachers , and fund the relocation of up to 200,000 villagers to minimize human-tiger conflicts. The number of tigers in India's wild has gone up by 20%, according to...
Read more

worksheet 1 Triangles

1.    Give two different examples of pair of (i) similar figures. (ii) non-similar figures. Solution: Two square of sides 4 cm and 8 cm each. A rhombus and a trapezium .   2.    State whether the following quadrilaterals are similar or not      Solution: Similar   3.    In the figure (i) and (ii), DE || BC. Find EC in (i) and AD in (ii). Solution: (i)   In  D ABC  DE is parallel to BC By Basic Proportionality Theorem  ------------------- (1) Given:  AD = 1.5 cm, DB = 3 cm, AE = 1 cm Let EC = ‘x’ cm Applying in (1) 1.5x = 3 x =  x = 2 cm EC = 2cm (ii) Since DE || BC, using BPT  …………………………. (1) Given: DB = 7.2 cm, AE = 1.8 cm, EC = 5.4 cm Let AD be = x sub. in (1) x =  =  \  AD = 2.4 cm   4.    E and F are points on the sides PQ and PR respectively of a Δ PQR. For each of the following cases, state whether EF || QR (i) PE = 3.9 cm, EQ = 3 ...
Read more