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Aight, always let it be etched on your mind that reference angles a.k.a. basic angles, usually symbolized by an alpha symbol, is an angle that lies in Quadrant 1 (reference angle < 90deg) and it starts in an anti/counterclockwise direction of OX. Whatever you do, make sure the reference angle is contained inside Quadrant 1. How to make it inside Quadrant 1? Well, I believe already knew - 180deg - theta (if theta falls in Q2), theta - 180deg (if theta falls in Q3), 360deg - theta (if theta falls in Q4) and you need not perform any operation if theta falls in Q1 - consider it the reference angle as it is < 90deg. On the other hand, let's say you want to find the reference angle for a negative angle, -theta, remember to omit the negative sign of the negative angle when subtracting to find the reference angle. You don't even need to put a -ive sign in front of 360deg or 180deg or any other special angles in which you're subtracting from or by. Just succinctly think it this way, to find the reference angle for a negative angle, the negative angle is mirrored or inversed to start from Q1 in a counterclockwise direction as usual. The reason to this is because if you experiment it yourself this example: sin (-390deg). [First], If you sketch a circle and make a -390deg revolution from QIV (clockwise direction), you'll notice that -390deg falls back in QIV. So, reference angle = (larger angle, i.e. 390deg) - (smaller angle, i.e. 360deg) = 30deg. Notice that I did not write -390 - (-360) because it will yield a -ive 30 instead. [Next], you wanna recall that only cos theta yields a +ive value in QIV so straightaway you know that sin (-390deg) is -ive. [Now for the intricate part,] check the answer for sin(-390deg) on your calculator. It says -0.5 true? Okay now that you know the value is -ive in QIV, include -ive sign in front of (sin 30deg); what do you get? -0.5 also correct? Okay so back to the question why you really don't want a -ive sign in front of reference angle, if you put -(sin -30deg), you'll get a +0.5 instead which is what you don't want. In a nutshell, just drop the -ive sign in front of -ive angles whenever you tryna find their reference angle. :P sorry too long i know! but helpful
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What do angles look like?
Right angles are 90 degrees. | | | | | _________ This is what a right angle looks like.
What do right angles look like?
Right angles are 90 degrees. | | | | | _________ This is what a right angle looks like.
The difference between complementary and supplementary angles?
Supplementary angles has the sum of the two angles that equal 180 degrees, while complementary angles have the sum of 90 degrees between two angles.Complementary angles sum to 90º, like 30º + 60º. Supplementary angles sum to 180º, like 45º and 135º.SUPPLEMENTARY ANGLES = the sum of the two angles are 180WHILECOMPLEMENTARY ANGLES= the sum of the two angles are 90
Total degrees in a square?
All internal angles of a quadrilateral like a square sum to 360 degrees.
How are right angles like acute angles?
An acute angle is an angle that is less than 90 degrees.
What are the angles on the decagon?
Provided the ten exterior angles sum to 360 degrees, any angle that you like.
What is angle of reference in trigonometry?
This is a VERY important question and I am glad you asked it. First you have to remember that in drawing angles we think of 4 quadrants. Think of the XY plane - the first quadrant is where BOTH X and Y are positive. In the 2nd quadrant the X is negative and the Y is positive. In the 3rd quadrant the X and the Y are negative. In the 4th quadrant the X is positive and the Y is negative. Normally when we draw an angle we draw an angle less than 90 degrees. However, we can draw any angle we want from 0 to 360. However that angle can be represented by an angle less than 90 degrees in a certain quadrant. Take an angle like 120 degrees. That angle is the same as a 60 degree angle in the 2nd quadrant. A 210 degree angle is the same as a 30 degree angle in the 3rd quadrant. A 359 degree angle is the same as a 1 degree angle in the 4th quadrant. Those smaller angles are reference angles. This explanation would be better if I could insert graphs. I have attached a link to a picture. Alpha is the angle and Beta is the reference angle.
How do you add angles?
Just like adding normal numbers. Example : 160 degrees + 40 degrees = 200 degrees
What you measure angles in?
Degrees You write it as a little circle like this: 180o
How many solid degrees are there in a sphere?
Spheres are measured with solid angles (which are like two dimensional angles). These angles can be measure with square degrees or steradians. A sphere measures 129300/π square degrees (or about 41,253 square degrees). A sphere measures 4π steradians (or about 12.566 steradians.)
How many degrees in a isosolese?
Like all triangles, the angles of an iscoceles add up to 180 degrees
A 'right' angles is how many degrees?
A 'right angle' looks like a corner, and measures 90 degrees.
