Question

Find x in the below diagram. What are such triangles called? [4 MARKS]

Answer 1

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Steps : 1 Mark
Result : 1 Mark
Name : 1 Mark

For a triangle, sum of all angles = 180${}^o$
Or, (2x - 15${}^o$) + (x + 20${}^o$) + (x + 15${}^o$) = 180${}^o$
Or, 2x + x + x - 15${}^o$ + 20${}^o$ + 15${}^o$ = 180${}^o$
Or, 4x + 20${}^o$ = 180${}^o$
Or, 4x = 160${}^o$
Or, x = $\frac{160}{4}$ = 40${}^o$

The angles of the triangle will be, 65${}^o$(2x - 15${}^o$), 60${}^o$(x + 20${}^o$) and 55${}^o$(x + 15${}^o$)
Since all angles are less than 90${}^o$, it's an acute angled triangle.