Chapter 13, Trigonometric Ratios and Functions - 13.2 Define General Angles and Use Radian Measure - 13.2 Exercises - Quiz for Lessons 13.1 and 13.2 - Page 865: 3

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Given: $B=70$ degrees $a=5$ Thus, $C=90$ It is a right triangle. Hence, the sum of two non-right angles of a triangle is 90 degrees: $B=90-A=90-70=20$ degrees We know $\tan B=\frac{b}{a}\\ \rightarrow b=a\tan B=5\times \tan 70\approx 13.74$ Apply the Pythagorean theorem to find c: $a^2+b^2=c^2\\c=\sqrt a^2+b^2\\c=\sqrt 5^2+(5\tan70)^2\approx14.62$