Question

In the given figure, AC = 13cm, BC = 12 cm and ∠B = 90°. Without using tables, find the values of: sin A cos A

Answer 1

ΔABC is a right-angled triangle.
∴ AC² = AB² + BC²
⇒ AB² 
= AC² - BC²
= 13² - 12²
= 169 - 144
= 25
⇒ AB = 5cm

sin A = `"BC"/"AC" = (12)/(13)`

cos A = `"AB"/"AC" = (5)/(13)`

sin A cos A 

= `(12)/(13) xx (5)/(13)`

= `(60)/(169)`.