Unit #5-05

Learning Outcome

At the end of this lesson, you will be able to:

• understand and use complex if ... then statement

Review

• what decision structures

Lesson

• nil

Daily Assignment

• create a program that lets the user input 3 lengths of a triangle and you will tell them what kind:

  • equilateral triangle

  • isosceles triangle

  • scalene triangle

• NOTE: we also need to ensure the sum of all the angles = 180° 

  • look at this Repl.it to see how to do that
    (or code below)

• HINT: the easiest way right now is probably to do an If ... Else if ... Else if ... Else if ... Else; and check if it really a triangle first!

Extra

• do the above program in PHP

const lengthAString = prompt("Enter length A of the triangle (mm):")

const lengthBString = prompt("Enter length A of the triangle (mm):")

const lengthCString = prompt("Enter length A of the triangle (mm):")

const lengthA = parseFloat(lengthAString)

const lengthB = parseFloat(lengthBString)

const lengthC = parseFloat(lengthCString)

// using the cosine law

const angleA = Math.acos((lengthB**2 + lengthC**2 - lengthA**2) / (2 * lengthB * lengthC)) * (180/Math.PI)

const angleB = Math.acos((lengthC**2 + lengthA**2 - lengthB**2) / (2 * lengthC * lengthA)) * (180/Math.PI)

const angleC = Math.acos((lengthA**2 + lengthB**2 - lengthC**2) / (2 * lengthA * lengthB)) * (180/Math.PI)

const sumOfAngles = Number((angleA).toFixed(2)) + Number((angleB).toFixed(2)) + Number((angleC).toFixed(2))

console.log(angleA)

console.log(angleB)

console.log(angleC)

console.log(sumOfAngles)