Mathematical notations are symbols and expressions used to represent mathematical results. For example, the notation "x = 5" represents the result of an equation where the value of x is 5. Similarly, the notation "√9 = 3" represents the result of taking the square root of 9, which equals 3. Mathematical notations help to communicate results in a concise and standardized way, making it easier for others to understand and work with the information. **

The notations in geometry typically represent different geometric shapes and properties. For example, "AB" represents a line segment with endpoints A and B, while "∠ABC" represents an angle formed by three points A, B, and C. "ΔABC" represents a triangle with vertices at points A, B, and C, and "π" represents the mathematical constant pi, which is approximately equal to 3.14159. These notations are used to describe and analyze the properties and relationships of geometric figures and angles. **

Guitar and keyboard chord notations are not the same. While both instruments use chord symbols to represent the combination of notes to be played together, the actual notation and positioning of the chords can differ. Guitar chord notations typically show the frets and strings to be played, while keyboard chord notations show the specific keys to be pressed. Additionally, the voicing and arrangement of the notes within the chord may vary between guitar and keyboard. **

The Big O notations for time complexity are used to describe the upper bound on the growth rate of an algorithm's running time as the input size increases. Some common Big O notations include O(1) for constant time complexity, O(log n) for logarithmic time complexity, O(n) for linear time complexity, O(n^2) for quadratic time complexity, and O(2^n) for exponential time complexity. These notations help in analyzing and comparing the efficiency of different algorithms. **

The two notations for acceleration in circular motion are centripetal acceleration and tangential acceleration. Centripetal acceleration is the acceleration directed towards the center of the circular path, and it is always perpendicular to the velocity of the object. Tangential acceleration, on the other hand, is the acceleration along the tangent of the circular path, and it can either increase or decrease the speed of the object. Both types of acceleration are important in understanding the motion of objects in circular paths. **

The two notations of vectors are column vectors and row vectors. Column vectors are arranged in a single column, while row vectors are arranged in a single row. The main difference between the two notations is their orientation - column vectors are vertical, while row vectors are horizontal. Both notations represent the same vector in terms of its components, but their arrangement differs. **

Cross-notations in an aria and a recitative refer to the use of musical motifs or themes from one section of an opera to another. In an aria, cross-notations can occur when a musical theme from an earlier part of the opera is reprised or referenced, creating a sense of continuity and connection between different parts of the work. In a recitative, cross-notations can occur when a musical motif is used to underscore a particular dramatic or emotional moment, providing a sense of unity and coherence to the overall narrative. These cross-notations help to unify the different elements of the opera and create a cohesive musical and dramatic experience for the audience. **

I'm sorry, but I cannot determine if the cool storage of electrical appliances is broken without more specific information. If you can provide more details about the specific appliance and the issue you are experiencing, I would be happy to try to help troubleshoot the problem. **