# Find out right the area???????

ABC is a isosceles triangle whose AB=AC=10cm. the angle BAC is 30 degrees. Find out the area of the triangle. ????

Note by Rahul Das
4 years, 9 months ago

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Use the sine formula for the area of the triangle. $$[ABC]=\frac{1}{2}(AB)(AC) \sin A$$.

- 4 years, 9 months ago

by using this formula: Area=1/2(AB)(AC)sinA. area=1/2(10)(10)1/2=25 cm^2

- 4 years, 9 months ago

area=1/21010*sin30=25 cm^2

- 4 years, 9 months ago

Using cosine law you will determine BC.After that using hero's formula you will determine the area of triangle

- 4 years, 9 months ago

25cm^2 as the formula is (1/2)(10)(10)(sin 30)=25 (sin 30 =1/2)

- 4 years, 9 months ago

Or, if you don't want trigonometry, draw $$AD$$ perpendicular to $$BC$$ at $$D$$. Since angles $$B$$ and $$C$$ both measure 75 degrees, you have no choice, but to use the ratio $$\frac{AD}{AB}=\frac{AD}{AC}=\frac{\sqrt{2}+\sqrt{6}}{4}$$ which still comes from trigonometry.

- 4 years, 9 months ago