• Communications of Mathematical Education
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• v.20 no.1 s.25
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• pp.9-18
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• 2006

In this paper we study on concept analogy of altitude and escribed circle of triangle. We start from following theorems related with sides of triangle: existence of triangle, Pythagoras theorem, cosine theorem, Heron formula. Using concept analogy of sides-altitudes, altitudes-escribed circle's radii we discover some properties of altitude and escribed circle's radii and prove these properties.

• Education of Primary School Mathematics
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• v.20 no.4
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• pp.305-319
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• 2017

In the process of finding the triangle height, 26 students in the 6th grade were surveyed to understand the students' triangle height through the eye movement data and to investigate the cognitive load of the students. As a result, the correctness rate of the pre-test was significantly increased in the post-test, and the frequency and retention of gaze data were smaller in the post-test than in the AOI of each question. The Participants's subjective cognitive load indicated that it was more difficult to understand the concept of rotated triangles compared with upright triangles that were parallel to the ground. More frequent and more retentions in the eye-tracking data were detected in the right triangles and acute triangles by rotating configuration. Eye movement data show that eye tracking technology can provide an objective measure of students' cognitive load for feedback on instructional design.

• Archives of Plastic Surgery
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• v.42 no.2
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• pp.226-231
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• 2015

The aim of this study is to consider breast imagery in art as depicted through western painting. Twenty western art paintings were collated. Most of the sample paintings were created from the mid-nineteenth century to the late twentieth century and some are from the Renaissance period. Ten anthropometric items were used to measure 15 distances between two landmarks and 3 angles between three points. The distance from the nipple to the sternal notch and to the midclavicular point was the same and they were 0.46 of the distance from the sternal notch to the umbilicus. The shape of the projection of the breast was almost an isosceles triangle and the altitude of the triangle was at a proportion of 0.45 of the bottom length and 0.16 of the distance from the sternal notch to the umbilicus. The distance between the lateral ends of the breasts was 2.14 times the facial width and the distance between nipples was 1.36 times the facial width. Proportions from works of art are more ideal and attractive than clinically measured proportions. The desirable ratios measured from historical paintings might be useful in planning breast surgeries.

• Journal of the Korean Institute of Navigation
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• v.13 no.2
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• pp.1-21
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• 1989

The computer can be used to display a continuously updated list or plot of vessel position. The computer that accept input data from a number of different navigation systems, e.g., Loran , Satnav, Radar, Decca, Compass, Sextant with electrical output etc., can compute the position of a vessel relative to prerecorded objects. The celestial navigation system requires the computer to do not much calculation. Calculation are for trigonometeric, linear systems, finding roots of nonlinear equation and least square estimation etc, . In order to computerize the celestrial navigation system, these calculations must be programmed. The purpose of this thesis is to study the formulation, the design and the test of calculations of the coordinates of celestial bodies, the altitude correction and the solution of the navigational triangle processes.

• Journal of the Korean School Mathematics Society
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• v.10 no.4
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• pp.519-533
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• 2007

In this paper we study a equality $\frac{1}{h_a}+\frac{1}{h_b}+\frac{1}{h_c}=\frac{1}{r}$ which contains altitudes and radius of inscribed circle of triangle. We search some paths for proving the equality, and find out 9 proof method of the equality which is related with descriptive geometry, coordinate geometry, and vector geometry.