Added Cosine Formula Calculator

[Anshika14528]

Fixes Issue🛠️

Closes #1035

Description👨‍💻

Added a Cosine Formula Calculator which is a web application that calculates the angle of triangle using cosine formula given a triangle ABC with sides a, b, c: Cos A=(b^2+c^2-a^2)/2bc. Cos B=(a^2+c^2-b^2)/2ac. Cos C=(a^2+b^2-c^2)/2ac.

Type of Change📄

• [x] New feature (non-breaking change which adds functionality)

Checklist✅

• [x] I am an Open Source contributor
• [x] I have performed a self-review of my code
• [x] My code follows the style guidelines of this project
• [x] I have commented on my code, particularly in hard-to-understand areas

Screenshots/GIF📷

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[github-actions[bot]]

Congrats, Your pull request has been successfully merged 🥳🎉 Thank you for your contribution to my project 🚀 Keep Contributing!! ✨ @Anshika14528