Finding an angle in an $80^\circ$-$80^\circ$-$20^\circ$ triangle ($60^\circ$-$70^\circ$ variant)
40615
Solve for $x$ in the $80^\circ$-$80^\circ$-$20^\circ$ triangle
94091
In $ \triangle ABC$ show that $ 1 \lt \cos A + \cos B + \cos C \le \frac 32$
106483
How to find angle x without calculator?
40952
Showing that sum of angles of hyperbolic triangle is strictly less than $\pi$
111815
Determine angle $x$ using only elementary geometry
130517
$ABCD$ is a square and $AEB$ is an equilateral triangle. Find $\angle DEC$.
116815
Angle between two circles
142673
Evaluate $\tan^{2}(20^{\circ}) + \tan^{2}(40^{\circ}) + \tan^{2}(80^{\circ})$
103988
Prove that $\tan20^°\tan40^°\tan60^°\tan80^°=3$
104176
$15x\equiv 20 \pmod{88}$ Euclid's algorithm
148963
The Ellipse Problem - finding an ellipse inside a triangle
45775
In a $\triangle ABC,$ Evaluation of minimum value of $\cot^2 A+\cot^2 B+\cot^2 C$
96065
Question about sines of angles in an acute triangle
73799
In a convex Quadrilateral ABCD, $\measuredangle ABC = \measuredangle BCD = 120^{\circ}$.Prove that: $ AC + BD \ge AB + BC + CD$
9479
$\sum \cos$ when angles are in arithmetic progression
23321
calculating angle in circle
27089
Find the radius of the inscribed circle of a right triangle.