Triangles

9000036101

Level: 
C
A \(3\, \mathrm{m}\) long rod is in a slant position with respect to the observer's eye: one end is in the distance \(20\, \mathrm{m}\) and the other one \(18\, \mathrm{m}\). Find the visual angle of the rod (the angle between the lines which connect the observer's eye and the ends of the rod) and round to the nearest degrees.
\(7^{\circ }\)
\(3^{\circ }\)
\(45^{\circ }\)
\(83^{\circ }\)

9000036102

Level: 
C
Three forces act on the same body in the same point and the total force on the body is zero (the forces cancel). The first two forces are \(8\, \mathrm{N}\) and \(10\, \mathrm{N}\) and the angle between these forces is \(55^{\circ }\). Find the third force.
\(16\, \mathrm{N}\)
\(15\, \mathrm{N}\)
\(17\, \mathrm{N}\)
\(18\, \mathrm{N}\)

9000036103

Level: 
C
Three forces \(F_{1}\), \(F_{2}\) and \(F_{3}\) act on the same body in the same point and the total force on the body is zero (the forces cancel). The first two forces are \(F_{1} = 8\, \mathrm{N}\) and \(F_{2} = 10\, \mathrm{N}\) and the angle between \(F_{1}\) and \(F_{2}\) is \(55^{\circ }\). Find the angle between \(F_{3}\) and \(F_{1}\). Round your answer to the nearest degrees.
\(149^{\circ }\)
\(125^{\circ }\)
\(55^{\circ }\)
\(30^{\circ }\)

9000036106

Level: 
C
Two straight roads go off from the crossing. The angle between directions of the roads is \(52^{\circ }18'\). A significant tree is on the first road in the distance \(250\, \mathrm{m}\) from the crossing. A rock with a beautiful view is on the second road in the distance \(380\, \mathrm{m}\) from the crossing. Find the direct distance (length of a line segment) from the rock to the tree and round your answer to nearest meters.
\(301\, \mathrm{m}\)
\(411\, \mathrm{m}\)
\(568\, \mathrm{m}\)
\(629\, \mathrm{m}\)

9000036107

Level: 
C
There are three information panels \(A\), \(B\) and \(C\) in the park. The direct distance between \(B\) and \(C\) is \(150\, \mathrm{m}\). The visual angle of this distance from the panel \(A\) is \(55^{\circ }\). The visual angle of the distance \(AC\) from the panel \(B\) is \(39^{\circ }\). Find the direct distance between the panels \(A\) and \(B\) and round your answer to nearest meters.
\(183\, \mathrm{m}\)
\(147\, \mathrm{m}\)
\(195\, \mathrm{m}\)
\(218\, \mathrm{m}\)

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.
\(19.3\, \mathrm{m}\)
\(18.2\, \mathrm{m}\)
\(18.9\, \mathrm{m}\)
\(19.5\, \mathrm{m}\)

9000036109

Level: 
C
The point \(A\) is located \(20\, \mathrm{cm}\) from a mirror and the point \(B\) is located \(50\, \mathrm{cm}\) from the same mirror. The direct distance between \(A\) and \(B\) (the length of the segment \(AB\)) is \(70\, \mathrm{cm}\). Find the angle of incidence of the ray through the point \(A\) which is reflected to the point \(B\) and round your answer to nearest degrees. (The angle of incidence is the angle between the incident ray and the normal to the mirror.)
\(42^{\circ }\)
\(37^{\circ }\)
\(38^{\circ }\)
\(48^{\circ }\)

9000036110

Level: 
C
A tower is observed from two different places \(A\) and \(B\). The direct distance between \(A\) and \(B\) is \(65\, \mathrm{m}\). If we denote the bottom of the tower by \(C\), we get a triangle \(ABC\) in which the measure of \(\measuredangle CAB \) is \(71^{\circ }\) and the measure of \(\measuredangle ABC \) is \( 34^{\circ }\). From the point \(A\) the angle of elevation of the top of the tower is \(40^{\circ }18'\). Find the height of the tower. Suppose that all \(A\), \(B\) and \(C\) are in the same height above sea level and round your answers to nearest meters.
\(32\, \mathrm{m}\)
\(30\, \mathrm{m}\)
\(35\, \mathrm{m}\)
\(38\, \mathrm{m}\)

9000038701

Level: 
C
The box is on the slope as in the picture. The angle of the slope is \(\alpha \). The forces acting on the box are the force of gravity \(\vec{F_{G}}\) and the friction \(\vec{F_{t}}\). The force of gravity can be replaced by two components \(\vec{F_{1}}\) and \(\vec{F_{n}}\). (The force \(\vec{F_{1}}\) is parallel to the slope and \(\vec{F_{n}}\) is perpendicular to the slope.) The friction \(F_{t}\) is given by the formula \(F_{t} = fF_{n}\), where \(f\) is the coefficient of the friction.What is the influence of the increasing angle \(\alpha \) on the forces acting on the box?
\(F_{1}\) becomes bigger and \(F_{t}\) becomes smaller
both \(F_{1}\) and \(F_{t}\) become smaller
\(F_{1}\) becomes bigger, \(F_{t}\) does not change
\(F_{1}\) becomes smaller, \(F_{t}\) does not change
both \(F_{1}\) and \(F_{t}\) become bigger
\(F_{1}\) becomes smaller and \(F_{t}\) becomes bigger