and this convention is still often followed, especially in elementary algebra. In geometry, capital A, B, C etc. are used to denote segments, lines, rays, etc. A capital A is also typically used as one of the letters to represent an angle in a triangle, the lowercase a representing the side opposite angle A. "A" is often used to denote something or someone of a better or more prestigious quality or status: A−, A or A+, the best grade that can be assigned by teachers for students' schoolwork; "A grade" for clean restaurants; A-list celebrities, etc. Such associations can have a motivating effect, as exposure to the letter A has been found to improve performance, when compared with other letters. "A" is used as a prefix on some words, such as asymmetry, to mean "not" or "without" (from Greek). In English grammar, "a", and its variant "an", is an indefinite article, used to introduce noun phrases. Finally, the letter A is used to denote size, as in a narrow size shoe, or a small cup size in a brassiere. Related characters Descendants and related characters in the Latin alphabet Æ æ : Latin AE ligature A with diacritics: Å å Ǻ ǻ Ḁ ḁ ẚ Ă ă Ặ ặ Ắ ắ Ằ ằ Ẳ ẳ Ẵ ẵ Ȃ ȃ Â â Ậ ậ Ấ ấ Ầ ầ Ẫ ẫ Ẩ ẩ Ả ả Ǎ ǎ Ⱥ ⱥ Ȧ ȧ Ǡ ǡ Ạ ạ Ä ä Ǟ ǟ À à Ȁ ȁ Á á Ā ā Ā̀ ā̀ Ã ã Ą ą Ą́ ą́ Ą̃ ą̃ A̲ a̲ ᶏ Phonetic alphabet symbols related to A (the International Phonetic Alphabet only uses lowercase, but uppercase forms are used in some other writing systems): Ɑ ɑ : Latin letter alpha / script A, which represents an open back unrounded vowel in the IPA ᶐ : Latin small letter alpha with retroflex hook Ɐ ɐ : Turned A, which represents a near-open central vowel in the IPA Λ ʌ : Turned V (also called a wedge, a caret, or a hat), which represents an open-mid back unrounded vowel in the IPA Ɒ ɒ : Turned alpha / script A, which represents an open back rounded vowel in the IPA ᶛ : Modifier letter small turned alpha ᴀ : Small capital A, an obsolete or non-standard symbol in the International Phonetic Alphabet used to represent