The area of triangle ABC ABC is 18 cm2. Side AC=4x AC = 4 x and side AB=x+3 AB = x + 3 . Given that angle A=30∘ , calculate the value of x

Respuesta :

Answer:

x = 3

Step-by-step explanation:

Let the altitude from B to AC intersect at point D.  Then BD is a height of the triangle with base AC

ΔABD is a 30-60-90 triangle since m∠A = 30

Therefore, AB = 2(BD)  or BD = AB/2 = (x+3)/2

Area of the triangle = bh/2 = AC(BD)/2 = 4x(x + 3)/(2)(2)

= x(x + 3) = 18

[tex]x^{2} + 3x = 18[/tex]

[tex]x^{2} + 3x - 18 = 0[/tex]

(x + 6)(x - 3) = 0

x = -6  or x = 3

x cannot equal -6, so x = 3

In this exercise we have to use the knowledge of triangle to calculate the value of X, in this way we find that:

[tex]X=3[/tex]

In this way, we can write the treated area of ​​the triangle as:

[tex]bh/2 = AC(BD)/2 = 4x(x + 3)/(2)(2)\\=x(x + 3) = 18\\x^2+3x=18\\x^2+3x-18=0\\(x+6)(x-3)=0\\x=-6 \ or \ x=3[/tex]

See more about triangle  at brainly.com/question/25813512