Sanchit DCMC

  MATHS  CIRCLES  10. Prove that the angle between the two tangents drawn from an external point to a circle is supplementary to the angle subtended by the line-segment joining the points of contact at the center. Answer: First, draw a circle with centre O. Choose an external point P and draw two tangents PA and PB at point A and point B respectively. Now, join A and B to make AB in a way that it subtends ∠AOB at the center of the circle. The diagram is as follows: From the above diagram, it is seen that the line segments OA and PA are perpendicular. So, ∠OAP = 90° In a similar way, the line segments OB ⊥ PB and so, ∠OBP = 90° Now, in the quadrilateral OAPB, ∴∠APB+∠OAP +∠PBO +∠BOA = 360° (since the sum of all interior angles will be 360°) By putting the values we get, ∠APB + 180° + ∠BOA = 360° So, ∠APB + ∠BOA = 180° (Hence proved).

  HINDI वर्तमान काल में वस्तुओं की बिक्री बढ़ाने एवं उनके उपभोग पर भरपूर जोर दिया जा रहा है। उत्पादक अपनी वस्तुओं की बिक्री द्वारा अधिकाधिक लाभ कमाना चाहते हैं तो उपभोक्ता उनका प्रयोग कर सुख एवं संतुष्टि पाना चाहता है। उपभोक्ताओं की इसी प्रवृत्ति का फायदा उठाने के लिए उत्पादक तरह-तरह के साधनों का सहारा लेते हैं। आज वस्तुओं की बिक्री बढ़ाने का प्रमुख हथियार विज्ञापन है। विज्ञापन शब्द ‘ज्ञापन’ में ‘वि’ उपसर्ग लगाने से बना है, जिसका अर्थ है-विशेष जानकारी देना। यह जानकारी उत्पादित वस्तुओं सेवाओं आदि से जुड़ी होती है। विज्ञापन में वस्तु के गुणों को बढ़ा-चढ़ाकर प्रस्तुत किया जाता है, जिससे उपभोक्ता लालायित हों और इन्हें खरीदने के लिए विवश हो जाएँ। विज्ञापन के कारण उत्पादकों को अपनी वस्तुओं के अच्छे दाम मिल जाते हैं तो उपभोक्ता को वस्तुओं की जानकारी, तुलनात्मक दाम एवं चयन का विकल्प मिल जाता है। आजकल टी.वी., रेडियो के कार्यक्रम, समाचार पत्र, पत्रिकाएँ, भवनों की दीवारें विज्ञापनों से रंगी दिखाई पड़ती हैं। विज्ञापन लेखन करते समय – एक बाक्स-सा बनाकर ऊपर मध्य में विज्ञापित वस्तु का नाम मोटे अक्षरो

LETTER FOR PLACING AN ORDER (FORMAT) Address Given Date Ref. No. _____________________ The Manager Name of company Address of company Subject: _____________________ Dear Sir/Madam Body of the letter Ref. to quotation dated List of requirement/items to be ordered Date on which delivery is required Mode of payment Items to be in good condition and as per requirement. Yours faithfully Name Designation

WHAT IS WEB SECURITY? Web Security also known as Cyber Security relates to the  securing of websites and servers from online risks . It is aimed at safeguarding the sensitive data by restricting, discovering and responding to attacks. The website security check involves scanning URL for potential vulnerabilities and malware through website security software. \ NEED OF WEB SECURITY As technology changes, it becomes increasingly challenging for businesses of all types to keep their personal and customer’s information on the web secure. Web security is important to keeping hackers and cyber-thieves from accessing sensitive information.  Without a proactive security strategy, businesses risk the spread and escalation of malware, attacks on other websites, networks, and other IT infrastructures. If a hacker is successful, attacks can spread from computer to computer, making it difficult to find the origin. CYBER THREAT   A cyber or cybersecurity threat is a malicious act that seeks to damag

Electromagnetic Induction or Induction is a process in which a  conductor  is put in a particular position and magnetic field keeps varying or  magnetic field  is stationary and a conductor is moving. This produces a Voltage or  EMF (Electromotive Force) across the electrical conductor. Michael Faraday discovered Law of Induction in 1830.  Through his experiment, he discovered that there are certain factors that influence this voltage production. They are: Number of Coils : The induced voltage is directly proportional to the number of turns/coils of the wire. Greater the number of turns, greater is voltage produced Changing Magnetic Field : Changing magnetic field affects the induced voltage. This can be done by either moving the magnetic field around the conductor or moving the conductor in the magnetic field. ELECTROMAGNETIC INDUCTION APPLICATIONS: Based on his experiments we now have   Faraday’s law   according to which   the amount of voltage induced in a coil is proportional to

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