CBSE ADDA

CBSE Exam  Congruence of  Triangle Solved Questions Q. 1. Prove that Sum of Two Sides of a triangle is greater than twice the length of median drawn to third side. Given:   Δ ABC in which AD is a median. To prove:   AB + AC > 2AD. Construction:   Produce AD to E, such that AD = DE. Join EC. Proof:   In ΔADB and ΔEDC, AD = DE              (Construction) BD = BD             (D is the mid point of BC) ∠ ADB = ∠ EDC       (Vertically opposite angles) ∴ ΔADB   ≅       ΔEDC   (SAS congruence criterion) ⇒ AB = ED               (CPCT) In ΔAEC, AC + ED > AE           ( Sum of any two sides of a triangles is greater than the third side ) ∴ AC + AB > 2AD      ( AE = AD + DE = AD + AD = 2AD & ED = AB ) Q. 2.  ABC is an isosceles triangle in which AB = AC. Side BA is produced to D such that AD = AB (see the given figure). Show that ∠ BCD is a right angle. In ΔABC, AB = AC

IX CBSE - Formative Assessment-II [SET-1] Q.1. What are green revolution and white revolution? Q.2. What nutrients do the following provide: (i) Pea (ii) Linseed (iii) Vegetables (iv) pigeon pea (v) Wheat (vi) Castor (vii) Spices (viii) fruits. Q.3. Differentiate between Kharif and Rabi crops. Q.4. What is interspecific hybridization? Q.5. How does change in maturity duration of crop help the framers? Q.6. Categorize the following as macronutrients and micronutrients: (i) Calcium (ii) Molybdenum (iii) Phosphorus (iv) Iron (v) Boron (vi) Magnesium. Q.7. What is organic farming? Q.8. What is vermicomposting? Q.9. Differentiate between mixed and inter cropping. Q10. What are river lift systems? Q.11. Why are weeds considered as unwanted plants in cultivated lands? Q.12. In what three ways do the pests attack plants? IX CBSE - Formative Assessment-II [SET-2] Q.1. What qualities are expected in a cross-breed variety of fowl? Q.2.

IX Class Question solution for Physics Chapter Sound 1. How sound is produced? Answer:   Sound is produced by the vibration of vibrating object. 2. What do you understand by a ‘wave’? Answer:  A periodic disturbance created in material medium that transfer sound and light energy is called wave. 3. Write three differences between sound and light waves. Answer:   sound wave is Mechanical wave that require material medium for propagation where as light waves are electromagnetic wave that can travel in vacuum. 4. What do you understand by “sound energy cannot be produced”? Answer: Sound energy cannot be produced on its own. Some mechanical energy is required to make an object vibrate. It is the mechanical energy of the vibrating object which travels through a medium and ultimately reaches the ear. 5. What is the name of the wave that can travel through vacuum? Answer:   Electromagnetic wave 6. Explain by some experiment that sound waves require medium for their