.
What will be the angle measures in an isosceles triangle that has a base of 30 and 
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 
= 15 inits each.
Now you have the right-angled triangle with one leg of 15 units and the hypotenuse of 17 units.
Hence, 
= 
where 
is the base angle of the original isosceles triangle.
Having this, find using your calculator, or computer, or trigonometric tables - whichever you have.
= 
.
