Question 1044010
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What will be the angle measures in an isosceles triangle that has a base of 30 and {{{highlight(cross(legs))}}} lateral sides of 17?
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Draw the altitude to the base in the triangle.
Since in an isosceles triangle the altitude to the base is the median in the same time, the altitude divides the base 
in two equal segments of {{{30/2}}} = 15 inits each.

Now you have the right-angled triangle with one leg of 15 units and the hypotenuse of 17 units.

Hence, {{{cos(alpha)}}} = {{{15/17}}} where {{{alpha}}} is the base angle of the original isosceles triangle.

Having this, find {{{alpha}}} using your calculator, or computer, or trigonometric tables - whichever you have.

{{{alpha}}} = {{{arccos(15/17)}}}.
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