How to find the angle of a triangle if you know two sides?

In a right triangle, you simply find the angle if you know two sides of him. One of the angles is equal to 90 degrees, the other two are always sharp. These angles and will need to find. In order to find an acute angle in a right triangle, you must know the values of all three sides. Depending on which side you are aware, the sinuses acute angles can be found using formulas for trigonometric functions. To find the angle values for the sine uses a four digit mathematical table.

You will need

• - Pythagorean Theorem;
• - trigonometric function sin;
• - four-digit mathematical tables Bradis.

Instruction

1. Use the following notation for ease of preparation of the formulas necessary for calculations: c is the hypotenuse of a right triangle; a, b are the legs that form a right angle, A is the acute angle opposite sides of b; B is the acute angle opposite of side a.
2. Calculate what is the length of the unknown side of the triangle. Apply for computing the Pythagorean theorem. Calculate the side a, if the known values of the hypotenuse c and leg b. To do this, subtract the square of the hypotenuse c, the square of side b and then calculate the square root of the result.
3. Calculate side b, if the known values of the hypotenuse c and a leg. To do this, subtract the square of the hypotenuse c, the square of side a, and then calculate the square root of the result.
4. Calculate the value of the hypotenuse c, if there are two sides. This will get the sum of the squares of the legs a and b and then calculate the square root of the result and, if necessary, rounded to four decimal places.
5. Calculate the sine of the angle A according to the formula sinA = a/c. Use for calculations the calculator. Rounded, if necessary, the value of the sine of the angle A to four decimal places.
6. Calculate the sine of the angle B by the formula sinB = b/c. Use for calculations the calculator. Rounded, if necessary, the value of the sine of the angle B to four decimal places.
7. Find the angles A and B by the values of their sines. Use to determine the values of the angles of table VIII four-digit mathematical tables Bradis. Find in this table the values of sine. Move from values to the left and the first column "And" take a degree. Move from the found values up and from the top row "And" take minutes. For example, if sin(A) = 0,8949, the angle A is 63 degrees 30 minutes.