# Construction Math

## Solving Unknown Lengths and Angles # IV Dual Pitched Roof

Solving the AnglesA dual pitched roof has the shape of a scalene triangle and as with all triangles, the combined three angles add up to 180 ° . From the two roof pitches you will be able to get the angles B and C.

Using the same known values as before:Roof pitch no 1 =^{9}/_{12}Roof pitch no 2 =^{5}/_{12}length a = 20'

##### Solving for angle B

Using the inverse Tan function for a 9/12 pitch. Divide the rise by the run^{9}/_{12}= 0.75 Arctan (0.75) = 36.8699 ° B = 36.9 ° (rounded to 1 digit) Angle B = 36.9 °

##### Solving for angle C

Using the inverse Tan function for a 5/12 pitch. Divide the rise by the run^{9}/_{12}= 0.416667 Arctan (0.41666667) = 22.6199 ° C = 22.6 ° (rounded to 1 digit) Angle C = 22.6 °

##### Solving for angle A

All the corners of the triangle have to add up to 180 °180 - 36.9(B) - 22.6(C) = 120.5 ° . Angle A = 120.5 °

##### Solving for angle ab

db = 90 ° and B = 36.9 ° ab = 180 - 90(db) - 36.9(B) = 53.1° Angle ab = 53.1°

##### Solving for angle ac:

A = 120.5 ° ab = 53.1° ac = 120.5 - 53.1 = 67.4 ° Angle ac = 67.4 °

### Angle of Roof From Roof Pitch

##### Construction Math Calculators

#### Area Calculation

#### Arithmetic

#### Estimating / Multiplier

#### Fractions and Decimals

#### How to do things

- Convert Feet in Decimal Format to Foot, Inch and Fraction
- Calculate the Square Footage of a Rectangle Shaped Area
- Equation Manipulation
- Calculating with Percentages

#### Solving a Duel Pitch

- What can you do with the roof pitch?
- Solving for length's aa and ab
- Calculating the Height
- Solving the Angles