Triangles

9000121705

Level: 
A
Consider an isosceles triangle \(ABC\) with sides \(AC\) and \(BC\) of equal length. The measure of the angle \( BAC\) is \(40^{\circ }\). \(X\) is the point of intersection between the line $AB$ and the line through the vertex \(C\) perpendicular to it. Find the measure of the angle \( BCX\).
\(50^{\circ }\)
\(80^{\circ }\)
\(100^{\circ }\)
\(40^{\circ }\)

9000045702

Level: 
B
Given a right triangle \(ABC\) (see the picture). Find the valid relation between the angle \(\alpha \) and the sides of the triangle.
\(\mathop{\mathrm{tg}}\nolimits \alpha = \frac{a} {c}\)
\(\sin \alpha = \frac{a} {c}\)
\(\cos \alpha = \frac{b} {a}\)
\(\mathop{\mathrm{cotg}}\nolimits \alpha = \frac{b} {a}\)

9000045703

Level: 
B
Given a right triangle \(ABC\) with the right angle at $C$ and an altitude $v$ (see the picture). Find the valid relation between the angle \(\alpha \) and the lengths in the triangle.
\(\sin \alpha = \frac{v} {b}\)
\(\sin \alpha = \frac{v} {c}\)
\(\sin \alpha = \frac{a} {v}\)
\(\sin \alpha = \frac{c} {a}\)

9000045704

Level: 
B
Given a right triangle \(ABC\) with the right angle at $C$ and an altitude $v$ (see the picture). Find the valid relation between the angle \(\beta \) and the lengths in the triangle.
\(\sin \beta = \frac{v} {a}\)
\(\mathop{\mathrm{tg}}\nolimits \beta = \frac{a} {v}\)
\(\cos \beta = \frac{v} {a}\)
\(\mathop{\mathrm{tg}}\nolimits \beta = \frac{v} {a}\)

9000046403

Level: 
B
Consider an isosceles triangle, i.e. the triangle with two sides of equal length. The length of the third side is \(4\, \mathrm{cm}\). One of the interior angles is \(120^{\circ }\). Find the area of this triangle.
\(\frac{4\sqrt{3}} {3} \, \mathrm{cm}^{2}\)
\(4\sqrt{3}\, \mathrm{cm}^{2}\)
\(\frac{8\sqrt{3}} {3} \, \mathrm{cm}^{2}\)

9000036108

Level: 
C
The center of a spherical balloon is at a height of \(500\, \mathrm{m}\) height. The visual angle of the balloon is \(1^{\circ }30'\). The elevation angle of the center of the balloon is \(42^{\circ }50'\). Find the diameter of the balloon in meters and round to nearest one decimal.
\(19.3\, \mathrm{m}\)
\(18.2\, \mathrm{m}\)
\(18.9\, \mathrm{m}\)
\(19.5\, \mathrm{m}\)