F triangle RST is an acute triangle, then m∠S must be less than 90°. equal to 90°. equal to 100°. greater than 90° and less than 180°.

Less than 90°. All acute angles in a triangle are less than 90°.

Given: Triangle RST is an acute triangle.

To Find: Angle S

Solution: As we know sum of angles of triangle is 180°.

Since the triangle is acute angled triangle

So, all angles of triangle must be less than 90°.

i. e ∠R<90°,∠S<90° and∠T<90°

So, Solution is ∠S<90°

Drawn an acute angled triangle below